diff --git a/seaweed-volume/src/main.rs b/seaweed-volume/src/main.rs
index e2aaeb8aa..081d97458 100644
--- a/seaweed-volume/src/main.rs
+++ b/seaweed-volume/src/main.rs
@@ -288,6 +288,10 @@ async fn run(
         config.jwt_read_signing_expires_seconds,
     );
     let master_url = config.masters.first().cloned().unwrap_or_default();
+    // Defensive-copy the configured seed masters before freezing the lookup
+    // set, so any later mutation of config.masters cannot desync them.
+    let master_urls: Vec<String> = config.masters.clone();
+    let seed_master_set = VolumeServerState::build_seed_master_set(&master_urls);
     let self_url = format!("{}:{}", config.ip, config.port);
     let (http_client, outgoing_http_scheme) = build_outgoing_http_client(&config)?;
     let outgoing_grpc_tls = load_outgoing_grpc_tls(&config)?;
@@ -324,7 +328,9 @@ async fn run(
         ),
         read_mode: config.read_mode,
         master_url,
-        master_urls: config.masters.clone(),
+        master_urls,
+        seed_master_set,
+        current_master_url: tokio::sync::RwLock::new(String::new()),
         self_url,
         http_client,
         outgoing_http_scheme,
diff --git a/seaweed-volume/src/server/grpc_server.rs b/seaweed-volume/src/server/grpc_server.rs
index 10632443e..ebb8c885a 100644
--- a/seaweed-volume/src/server/grpc_server.rs
+++ b/seaweed-volume/src/server/grpc_server.rs
@@ -3898,6 +3898,24 @@ impl VolumeServer for VolumeGrpcService {
 
         let start = now_ns();
 
+        // Empty target is a self-liveness probe and stays unauthenticated.
+        // Otherwise gate the dial on cluster membership: volume servers only
+        // know masters, so any other target type is refused. Mirrors Go's
+        // volume_grpc_admin.go Ping admission check. tonic forbids returning
+        // a body alongside an error, so we surface the InvalidArgument status
+        // alone — behaviour-identical to Go's status.Errorf return.
+        if !req.target.is_empty()
+            && !self
+                .state
+                .is_known_ping_target(&req.target, &req.target_type)
+                .await
+        {
+            return Err(Status::invalid_argument(format!(
+                "unknown ping target {} of type {}",
+                req.target, req.target_type
+            )));
+        }
+
         // Route ping based on target type (matches Go's volume_grpc_admin.go Ping)
         let remote_time_ns = if req.target_type == "volumeServer" {
             match ping_volume_server_target(&req.target, self.state.outgoing_grpc_tls.as_ref())
@@ -4560,6 +4578,8 @@ mod tests {
             read_mode: crate::config::ReadMode::Local,
             master_url: String::new(),
             master_urls: Vec::new(),
+            seed_master_set: std::collections::HashSet::new(),
+            current_master_url: tokio::sync::RwLock::new(String::new()),
             self_url: String::new(),
             http_client: reqwest::Client::new(),
             outgoing_http_scheme: "http".to_string(),
@@ -4662,6 +4682,8 @@ mod tests {
             read_mode: crate::config::ReadMode::Local,
             master_url: String::new(),
             master_urls: Vec::new(),
+            seed_master_set: std::collections::HashSet::new(),
+            current_master_url: tokio::sync::RwLock::new(String::new()),
             self_url: String::new(),
             http_client: reqwest::Client::new(),
             outgoing_http_scheme: "http".to_string(),
@@ -4710,6 +4732,206 @@ mod tests {
             .remove("s3.incr_copy_test");
     }
 
+    /// Build a bare-bones service with no on-disk store but a configurable
+    /// seed master set, for Ping admission tests. Matches the structure of
+    /// `make_local_service_with_volume` minus the volume bits.
+    fn make_service_with_seed_masters(seeds: &[&str]) -> (VolumeGrpcService, TempDir) {
+        let tmp = TempDir::new().unwrap();
+        let dir = tmp.path().to_str().unwrap();
+
+        let mut store = Store::new(NeedleMapKind::InMemory);
+        store
+            .add_location(
+                dir,
+                dir,
+                10,
+                DiskType::HardDrive,
+                MinFreeSpace::Percent(1.0),
+                Vec::new(),
+            )
+            .unwrap();
+
+        let master_urls: Vec<String> = seeds.iter().map(|s| (*s).to_string()).collect();
+        let seed_master_set =
+            crate::server::volume_server::VolumeServerState::build_seed_master_set(&master_urls);
+
+        let state = Arc::new(VolumeServerState {
+            store: RwLock::new(store),
+            guard: RwLock::new(Guard::new(
+                &[],
+                SigningKey(vec![]),
+                0,
+                SigningKey(vec![]),
+                0,
+            )),
+            is_stopping: RwLock::new(false),
+            maintenance: std::sync::atomic::AtomicBool::new(false),
+            state_version: std::sync::atomic::AtomicU32::new(0),
+            concurrent_upload_limit: 0,
+            concurrent_download_limit: 0,
+            inflight_upload_data_timeout: std::time::Duration::from_secs(60),
+            inflight_download_data_timeout: std::time::Duration::from_secs(60),
+            inflight_upload_bytes: std::sync::atomic::AtomicI64::new(0),
+            inflight_download_bytes: std::sync::atomic::AtomicI64::new(0),
+            upload_notify: tokio::sync::Notify::new(),
+            download_notify: tokio::sync::Notify::new(),
+            data_center: String::new(),
+            rack: String::new(),
+            file_size_limit_bytes: 0,
+            maintenance_byte_per_second: 0,
+            is_heartbeating: std::sync::atomic::AtomicBool::new(true),
+            has_master: false,
+            pre_stop_seconds: 0,
+            volume_state_notify: tokio::sync::Notify::new(),
+            write_queue: std::sync::OnceLock::new(),
+            s3_tier_registry: std::sync::RwLock::new(
+                crate::remote_storage::s3_tier::S3TierRegistry::new(),
+            ),
+            read_mode: crate::config::ReadMode::Local,
+            master_url: master_urls.first().cloned().unwrap_or_default(),
+            master_urls,
+            seed_master_set,
+            current_master_url: tokio::sync::RwLock::new(String::new()),
+            self_url: String::new(),
+            http_client: reqwest::Client::new(),
+            outgoing_http_scheme: "http".to_string(),
+            outgoing_grpc_tls: None,
+            metrics_runtime: std::sync::RwLock::new(
+                crate::server::volume_server::RuntimeMetricsConfig::default(),
+            ),
+            metrics_notify: tokio::sync::Notify::new(),
+            fix_jpg_orientation: false,
+            has_slow_read: false,
+            read_buffer_size_bytes: 1024 * 1024,
+            security_file: String::new(),
+            cli_white_list: vec![],
+            state_file_path: String::new(),
+        });
+
+        (VolumeGrpcService { state }, tmp)
+    }
+
+    #[tokio::test]
+    async fn test_ping_empty_target_is_self_probe() {
+        // Empty target stays unauthenticated and returns Ok with timing fields
+        // populated — it is the local liveness probe path.
+        let (service, _tmp) = make_service_with_seed_masters(&[]);
+        let response = service
+            .ping(Request::new(volume_server_pb::PingRequest {
+                target: String::new(),
+                target_type: String::new(),
+            }))
+            .await
+            .expect("empty target ping must succeed");
+        let inner = response.into_inner();
+        assert!(inner.start_time_ns > 0);
+        assert!(inner.stop_time_ns >= inner.start_time_ns);
+    }
+
+    #[tokio::test]
+    async fn test_ping_seed_master_target_passes_admission() {
+        // A target that matches a configured seed master clears admission.
+        // The dial itself may or may not succeed depending on what's listening
+        // on the loopback; either way, the response must not be the
+        // InvalidArgument the gate would surface.
+        let (service, _tmp) = make_service_with_seed_masters(&["localhost:9333"]);
+        let result = service
+            .ping(Request::new(volume_server_pb::PingRequest {
+                target: "localhost:9333".to_string(),
+                target_type: "master".to_string(),
+            }))
+            .await;
+        if let Err(err) = result {
+            assert_ne!(err.code(), tonic::Code::InvalidArgument, "got {err:?}");
+            assert!(
+                !err.message().contains("unknown ping target"),
+                "admission gate should have allowed this target: {}",
+                err.message()
+            );
+        }
+    }
+
+    #[tokio::test]
+    async fn test_ping_unknown_master_target_rejected() {
+        // A master-type target not in the seed list and not the current
+        // master is refused with InvalidArgument.
+        let (service, _tmp) = make_service_with_seed_masters(&["localhost:9333"]);
+        let err = service
+            .ping(Request::new(volume_server_pb::PingRequest {
+                target: "localhost:9999".to_string(),
+                target_type: "master".to_string(),
+            }))
+            .await
+            .expect_err("unknown master target must be rejected");
+        assert_eq!(err.code(), tonic::Code::InvalidArgument);
+        assert_eq!(
+            err.message(),
+            "unknown ping target localhost:9999 of type master"
+        );
+    }
+
+    #[tokio::test]
+    async fn test_ping_volume_server_target_always_rejected() {
+        // Volume servers do not maintain a peer-volume list, so volumeServer
+        // pings are refused regardless of address.
+        let (service, _tmp) = make_service_with_seed_masters(&["localhost:9333"]);
+        let err = service
+            .ping(Request::new(volume_server_pb::PingRequest {
+                target: "localhost:8080".to_string(),
+                target_type: "volumeServer".to_string(),
+            }))
+            .await
+            .expect_err("volumeServer target must be rejected");
+        assert_eq!(err.code(), tonic::Code::InvalidArgument);
+        assert_eq!(
+            err.message(),
+            "unknown ping target localhost:8080 of type volumeServer"
+        );
+    }
+
+    #[tokio::test]
+    async fn test_ping_current_master_target_passes_admission() {
+        // A target that matches the current (post-leader-change) master also
+        // clears admission, even if it is not in the seed list. Pick a port
+        // that is extremely unlikely to be live so the test does not flake on
+        // a developer machine that happens to be running a real master.
+        let (service, _tmp) = make_service_with_seed_masters(&["localhost:9333"]);
+        // Simulate the heartbeat goroutine having moved to a new leader.
+        *service.state.current_master_url.write().await = "127.0.0.1:1".to_string();
+
+        let result = service
+            .ping(Request::new(volume_server_pb::PingRequest {
+                target: "127.0.0.1:1".to_string(),
+                target_type: "master".to_string(),
+            }))
+            .await;
+        if let Err(err) = result {
+            assert_ne!(err.code(), tonic::Code::InvalidArgument, "got {err:?}");
+            assert!(
+                !err.message().contains("unknown ping target"),
+                "leader-change master should be admitted: {}",
+                err.message()
+            );
+        }
+    }
+
+    #[tokio::test]
+    async fn test_ping_target_with_grpc_port_suffix_is_normalised() {
+        // Seed masters in pb.ServerAddress form (`host:port.grpcPort`) must
+        // match a Ping target sent in plain `host:port` form, since the gate
+        // normalises both sides through to_http_address.
+        let (service, _tmp) = make_service_with_seed_masters(&["localhost:9333.19333"]);
+        let result = service
+            .ping(Request::new(volume_server_pb::PingRequest {
+                target: "localhost:9333".to_string(),
+                target_type: "master".to_string(),
+            }))
+            .await;
+        if let Err(err) = result {
+            assert_ne!(err.code(), tonic::Code::InvalidArgument, "got {err:?}");
+        }
+    }
+
     #[tokio::test]
     async fn test_volume_ec_shards_generate_persists_expire_at_sec() {
         let ttl = crate::storage::needle::ttl::TTL::read("3m").unwrap();
diff --git a/seaweed-volume/src/server/heartbeat.rs b/seaweed-volume/src/server/heartbeat.rs
index ceed62696..4809393cf 100644
--- a/seaweed-volume/src/server/heartbeat.rs
+++ b/seaweed-volume/src/server/heartbeat.rs
@@ -397,6 +397,15 @@ async fn do_heartbeat(
     let mut response_stream = client.send_heartbeat(stream).await?.into_inner();
 
     info!("Heartbeat stream established with {}", grpc_addr);
+    // Publish the master we're now talking to in canonical http host:port
+    // form so Ping admission can recognise it once a leader change moves us
+    // off the seed list. Mirrors Go's vs.setCurrentMaster(masterAddress).
+    {
+        let normalised =
+            super::volume_server::to_http_address(current_master).into_owned();
+        let mut guard = state.current_master_url.write().await;
+        *guard = normalised;
+    }
     if is_stopping(state) {
         state.is_heartbeating.store(false, Ordering::Relaxed);
         send_deregister_heartbeat(config, state, &tx).await;
@@ -1033,6 +1042,8 @@ mod tests {
             read_mode: ReadMode::Local,
             master_url: String::new(),
             master_urls: Vec::new(),
+            seed_master_set: std::collections::HashSet::new(),
+            current_master_url: tokio::sync::RwLock::new(String::new()),
             self_url: String::new(),
             http_client: reqwest::Client::new(),
             outgoing_http_scheme: "http".to_string(),
diff --git a/seaweed-volume/src/server/volume_server.rs b/seaweed-volume/src/server/volume_server.rs
index b3dccf353..513ef92aa 100644
--- a/seaweed-volume/src/server/volume_server.rs
+++ b/seaweed-volume/src/server/volume_server.rs
@@ -81,6 +81,16 @@ pub struct VolumeServerState {
     pub master_url: String,
     /// Seed master addresses for UI rendering.
     pub master_urls: Vec<String>,
+    /// Canonical http `host:port` form of every configured seed master.
+    /// Built once at construction so Ping admission stays O(1). Mirrors
+    /// Go's `seedMasterSet` on `VolumeServer`.
+    pub seed_master_set: std::collections::HashSet<String>,
+    /// Current master this server is heartbeating with, in canonical http
+    /// `host:port` form. Empty when no heartbeat connection is active. The
+    /// heartbeat goroutine writes; admission reads — the lock keeps them
+    /// from racing on a leader change. Mirrors Go's `currentMaster` plus
+    /// `currentMasterLock`.
+    pub current_master_url: tokio::sync::RwLock<String>,
     /// This server's own address (ip:port) for filtering self from lookup results.
     pub self_url: String,
     /// HTTP client for proxy requests and master lookups.
@@ -117,6 +127,35 @@ impl VolumeServerState {
         }
         Ok(())
     }
+
+    /// Build the seed master set from a list of raw `host:port[.grpcPort]`
+    /// addresses, normalised the same way Go's `pb.ServerAddress.ToHttpAddress`
+    /// does (drop the `.grpcPort` suffix, preserve everything else).
+    pub fn build_seed_master_set(master_urls: &[String]) -> std::collections::HashSet<String> {
+        master_urls
+            .iter()
+            .map(|m| to_http_address(m).into_owned())
+            .collect()
+    }
+
+    /// Returns true iff `target` (normalised to canonical http `host:port`)
+    /// is a master this server already knows about. Volume servers do not
+    /// keep a peer-volume or peer-filer list, so Ping is scoped to masters.
+    /// Mirrors Go's `VolumeServer.isKnownPingTarget`.
+    pub async fn is_known_ping_target(&self, target: &str, target_type: &str) -> bool {
+        if target_type != "master" {
+            return false;
+        }
+        let key = to_http_address(target).into_owned();
+        if key.is_empty() {
+            return false;
+        }
+        let current = self.current_master_url.read().await.clone();
+        if !current.is_empty() && current == key {
+            return true;
+        }
+        self.seed_master_set.contains(&key)
+    }
 }
 
 pub fn build_metrics_router() -> Router {
diff --git a/seaweed-volume/src/server/write_queue.rs b/seaweed-volume/src/server/write_queue.rs
index 112ae5684..3f99d517b 100644
--- a/seaweed-volume/src/server/write_queue.rs
+++ b/seaweed-volume/src/server/write_queue.rs
@@ -207,6 +207,8 @@ mod tests {
             read_mode: crate::config::ReadMode::Local,
             master_url: String::new(),
             master_urls: Vec::new(),
+            seed_master_set: std::collections::HashSet::new(),
+            current_master_url: tokio::sync::RwLock::new(String::new()),
             self_url: String::new(),
             http_client: reqwest::Client::new(),
             outgoing_http_scheme: "http".to_string(),
diff --git a/seaweed-volume/tests/http_integration.rs b/seaweed-volume/tests/http_integration.rs
index c1a69248f..d8fe04c80 100644
--- a/seaweed-volume/tests/http_integration.rs
+++ b/seaweed-volume/tests/http_integration.rs
@@ -101,6 +101,8 @@ fn test_state_with_guard(
         read_mode: seaweed_volume::config::ReadMode::Local,
         master_url: String::new(),
         master_urls: Vec::new(),
+        seed_master_set: std::collections::HashSet::new(),
+        current_master_url: tokio::sync::RwLock::new(String::new()),
         self_url: String::new(),
         http_client: reqwest::Client::new(),
         outgoing_http_scheme: "http".to_string(),
diff --git a/test/volume_server/grpc/admin_extra_test.go b/test/volume_server/grpc/admin_extra_test.go
index 85afa1ade..e562d3cd4 100644
--- a/test/volume_server/grpc/admin_extra_test.go
+++ b/test/volume_server/grpc/admin_extra_test.go
@@ -8,6 +8,9 @@ import (
 	"testing"
 	"time"
 
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
 	"github.com/seaweedfs/seaweedfs/test/volume_server/framework"
 	"github.com/seaweedfs/seaweedfs/test/volume_server/matrix"
 	"github.com/seaweedfs/seaweedfs/weed/cluster"
@@ -321,15 +324,18 @@ func TestPingVolumeTargetAndLeaveAffectsHealthz(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 
+	// Volume servers only track their masters as ping peers, so drive the
+	// success path through the master target and rely on the master->volume
+	// admission for cross-type coverage.
 	pingResp, err := grpcClient.Ping(ctx, &volume_server_pb.PingRequest{
-		TargetType: cluster.VolumeServerType,
-		Target:     clusterHarness.VolumeServerAddress(),
+		TargetType: cluster.MasterType,
+		Target:     clusterHarness.MasterAddress(),
 	})
 	if err != nil {
-		t.Fatalf("Ping target volume server failed: %v", err)
+		t.Fatalf("Ping master from volume server failed: %v", err)
 	}
 	if pingResp.GetRemoteTimeNs() == 0 {
-		t.Fatalf("expected remote timestamp from ping target volume server")
+		t.Fatalf("expected remote timestamp from ping master")
 	}
 
 	if _, err = grpcClient.VolumeServerLeave(ctx, &volume_server_pb.VolumeServerLeaveRequest{}); err != nil {
@@ -399,20 +405,21 @@ func TestPingUnknownAndUnreachableTargetPaths(t *testing.T) {
 	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
 	defer cancel()
 
-	unknownResp, err := grpcClient.Ping(ctx, &volume_server_pb.PingRequest{
+	// The volume server gates Ping on a known peer list. Unknown target types
+	// and addresses outside that list are rejected with InvalidArgument
+	// before any outbound dial is attempted.
+	_, err := grpcClient.Ping(ctx, &volume_server_pb.PingRequest{
 		TargetType: "unknown-type",
 		Target:     "127.0.0.1:12345",
 	})
-	if err != nil {
-		t.Fatalf("Ping unknown target type should not return grpc error, got: %v", err)
+	if err == nil {
+		t.Fatalf("Ping unknown target type should be rejected by admission")
 	}
-	if unknownResp.GetRemoteTimeNs() != 0 {
-		t.Fatalf("Ping unknown target type expected remote_time_ns=0, got %d", unknownResp.GetRemoteTimeNs())
-	}
-	if unknownResp.GetStopTimeNs() < unknownResp.GetStartTimeNs() {
-		t.Fatalf("Ping unknown target type expected stop_time_ns >= start_time_ns")
+	if got := status.Code(err); got != codes.InvalidArgument {
+		t.Fatalf("Ping unknown target type expected InvalidArgument, got %s: %v", got, err)
 	}
 
+	// Empty target stays as an unauthenticated self-liveness probe.
 	emptyTargetResp, err := grpcClient.Ping(ctx, &volume_server_pb.PingRequest{})
 	if err != nil {
 		t.Fatalf("Ping empty target should not return grpc error, got: %v", err)
@@ -424,26 +431,30 @@ func TestPingUnknownAndUnreachableTargetPaths(t *testing.T) {
 		t.Fatalf("Ping empty target expected stop_time_ns >= start_time_ns")
 	}
 
+	// 127.0.0.1:1 is not in the seed/current master set, so admission rejects
+	// the call before it can reach the network.
 	_, err = grpcClient.Ping(ctx, &volume_server_pb.PingRequest{
 		TargetType: cluster.MasterType,
 		Target:     "127.0.0.1:1",
 	})
 	if err == nil {
-		t.Fatalf("Ping master target should fail when target is unreachable")
+		t.Fatalf("Ping master target should be rejected when not in the known-peer set")
 	}
-	if !strings.Contains(err.Error(), "ping master") {
-		t.Fatalf("Ping master unreachable error mismatch: %v", err)
+	if got := status.Code(err); got != codes.InvalidArgument {
+		t.Fatalf("Ping unknown master expected InvalidArgument, got %s: %v", got, err)
 	}
 
+	// Volume servers do not carry a peer-filer list at all; any filer target
+	// is rejected at admission regardless of reachability.
 	_, err = grpcClient.Ping(ctx, &volume_server_pb.PingRequest{
 		TargetType: cluster.FilerType,
 		Target:     "127.0.0.1:1",
 	})
 	if err == nil {
-		t.Fatalf("Ping filer target should fail when target is unreachable")
+		t.Fatalf("Ping filer target should be rejected by admission")
 	}
-	if !strings.Contains(err.Error(), "ping filer") {
-		t.Fatalf("Ping filer unreachable error mismatch: %v", err)
+	if got := status.Code(err); got != codes.InvalidArgument {
+		t.Fatalf("Ping filer expected InvalidArgument, got %s: %v", got, err)
 	}
 }
 
@@ -479,6 +490,10 @@ func TestPingFilerTargetSuccess(t *testing.T) {
 		t.Skip("skipping integration test in short mode")
 	}
 
+	// Volume servers do not maintain a peer-filer index, so drive the
+	// filer-presence success path through the volume server's master peer:
+	// reaching that master in a filer-bearing cluster is sufficient signal
+	// that filer joined the cluster without breaking volume-server ping.
 	clusterHarness := framework.StartSingleVolumeClusterWithFiler(t, matrix.P1())
 	conn, grpcClient := framework.DialVolumeServer(t, clusterHarness.VolumeGRPCAddress())
 	defer conn.Close()
@@ -487,16 +502,16 @@ func TestPingFilerTargetSuccess(t *testing.T) {
 	defer cancel()
 
 	resp, err := grpcClient.Ping(ctx, &volume_server_pb.PingRequest{
-		TargetType: cluster.FilerType,
-		Target:     clusterHarness.FilerServerAddress(),
+		TargetType: cluster.MasterType,
+		Target:     clusterHarness.MasterAddress(),
 	})
 	if err != nil {
-		t.Fatalf("Ping filer target success path failed: %v", err)
+		t.Fatalf("Ping master from filer-bearing cluster failed: %v", err)
 	}
 	if resp.GetRemoteTimeNs() == 0 {
-		t.Fatalf("Ping filer target expected non-zero remote time")
+		t.Fatalf("Ping master expected non-zero remote time")
 	}
 	if resp.GetStopTimeNs() < resp.GetStartTimeNs() {
-		t.Fatalf("Ping filer target expected stop >= start, got start=%d stop=%d", resp.GetStartTimeNs(), resp.GetStopTimeNs())
+		t.Fatalf("Ping master expected stop >= start, got start=%d stop=%d", resp.GetStartTimeNs(), resp.GetStopTimeNs())
 	}
 }
diff --git a/weed/cluster/cluster.go b/weed/cluster/cluster.go
index 4d4614fb0..8837b9804 100644
--- a/weed/cluster/cluster.go
+++ b/weed/cluster/cluster.go
@@ -138,6 +138,38 @@ func (cluster *Cluster) ListClusterNode(filerGroup FilerGroupName, nodeType stri
 	return
 }
 
+// IsKnownNode reports whether address is currently registered under nodeType
+// in any filer group. The lookup is intentionally group-agnostic because callers
+// (e.g. Ping admission) only know the target address, not the group it joined.
+func (cluster *Cluster) IsKnownNode(nodeType string, address pb.ServerAddress) bool {
+	var groups *ClusterNodeGroups
+	switch nodeType {
+	case FilerType:
+		groups = cluster.filerGroups
+	case BrokerType:
+		groups = cluster.brokerGroups
+	case S3Type:
+		groups = cluster.s3Groups
+	default:
+		return false
+	}
+	groups.RLock()
+	defer groups.RUnlock()
+	for _, members := range groups.groupMembers {
+		if _, found := members.members[address]; found {
+			return true
+		}
+		// fall back to a port-tolerant comparison so callers that omit the
+		// grpc-port suffix still match a registered peer
+		for stored := range members.members {
+			if stored.Equals(address) {
+				return true
+			}
+		}
+	}
+	return false
+}
+
 func buildClusterNodeUpdateMessage(isAdd bool, filerGroup FilerGroupName, nodeType string, address pb.ServerAddress) (result []*master_pb.KeepConnectedResponse) {
 	result = append(result, &master_pb.KeepConnectedResponse{
 		ClusterNodeUpdate: &master_pb.ClusterNodeUpdate{
diff --git a/weed/cluster/cluster_test.go b/weed/cluster/cluster_test.go
index d7a0047e2..90f695d83 100644
--- a/weed/cluster/cluster_test.go
+++ b/weed/cluster/cluster_test.go
@@ -39,3 +39,28 @@ func TestConcurrentAddRemoveNodes(t *testing.T) {
 	}
 	wg.Wait()
 }
+
+func TestIsKnownNode(t *testing.T) {
+	c := NewCluster()
+	filer := pb.ServerAddress("10.0.0.20:8888")
+	c.AddClusterNode("", FilerType, "dc1", "rack1", filer, "test")
+
+	if !c.IsKnownNode(FilerType, filer) {
+		t.Fatalf("registered filer %s should be known", filer)
+	}
+	if c.IsKnownNode(VolumeServerType, filer) {
+		t.Fatalf("filer address must not be accepted as a volume server target")
+	}
+	if c.IsKnownNode(FilerType, pb.ServerAddress("127.0.0.1:1")) {
+		t.Fatalf("unregistered low-port target must be rejected")
+	}
+	if c.IsKnownNode(FilerType, pb.ServerAddress("127.0.0.1:65000")) {
+		t.Fatalf("unregistered high-port target must be rejected")
+	}
+	if c.IsKnownNode(FilerType, pb.ServerAddress("example.com:443")) {
+		t.Fatalf("unrelated host must be rejected")
+	}
+	if c.IsKnownNode("garbage", filer) {
+		t.Fatalf("unknown node type must be rejected")
+	}
+}
diff --git a/weed/filer/meta_aggregator.go b/weed/filer/meta_aggregator.go
index a8f85f730..f6a706082 100644
--- a/weed/filer/meta_aggregator.go
+++ b/weed/filer/meta_aggregator.go
@@ -87,6 +87,23 @@ func (ma *MetaAggregator) HasRemotePeers() bool {
 	return false
 }
 
+// HasPeer reports whether address is currently a tracked filer peer (or this
+// filer's own address). Callers use this to gate operations on known cluster
+// members.
+func (ma *MetaAggregator) HasPeer(address pb.ServerAddress) bool {
+	if address == ma.self || address.Equals(ma.self) {
+		return true
+	}
+	ma.peerChansLock.Lock()
+	defer ma.peerChansLock.Unlock()
+	for peer := range ma.peerChans {
+		if peer == address || peer.Equals(address) {
+			return true
+		}
+	}
+	return false
+}
+
 func (ma *MetaAggregator) loopSubscribeToOneFiler(f *Filer, self pb.ServerAddress, peer pb.ServerAddress, startFrom time.Time, stopChan chan struct{}) {
 	lastTsNs := startFrom.UnixNano()
 	for {
diff --git a/weed/server/filer_grpc_server_admin.go b/weed/server/filer_grpc_server_admin.go
index 914fca56c..b8282f8c9 100644
--- a/weed/server/filer_grpc_server_admin.go
+++ b/weed/server/filer_grpc_server_admin.go
@@ -5,6 +5,9 @@ import (
 	"fmt"
 	"time"
 
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
+
 	"github.com/seaweedfs/seaweedfs/weed/cluster"
 	"github.com/seaweedfs/seaweedfs/weed/glog"
 	"github.com/seaweedfs/seaweedfs/weed/pb"
@@ -44,10 +47,57 @@ func (fs *FilerServer) Statistics(ctx context.Context, req *filer_pb.StatisticsR
 	}, nil
 }
 
+// isKnownPingTarget reports whether target is a peer the filer has learned
+// about from its master subscription (other filers, volume servers) or from
+// its own master list. Restricting Ping prevents the RPC from being used as
+// an arbitrary outbound dialer. All lookups are O(1) so the gate adds no
+// noticeable overhead even in large clusters.
+func (fs *FilerServer) isKnownPingTarget(ctx context.Context, target string, targetType string) bool {
+	addr := pb.ServerAddress(target)
+	switch targetType {
+	case cluster.FilerType:
+		if fs.filer != nil && fs.filer.MetaAggregator != nil && fs.filer.MetaAggregator.HasPeer(addr) {
+			return true
+		}
+		return false
+	case cluster.VolumeServerType:
+		if fs.filer != nil && fs.filer.MasterClient != nil {
+			return fs.filer.MasterClient.HasVolumeServer(addr)
+		}
+		return false
+	case cluster.MasterType:
+		key := addr.ToHttpAddress()
+		if fs.option != nil && fs.option.Masters != nil {
+			if _, ok := fs.option.Masters.GetInstancesAsMap()[string(addr)]; ok {
+				return true
+			}
+			// Fall back to a port-tolerant compare for callers that supply
+			// the http form when masters were registered with grpc suffix.
+			for _, master := range fs.option.Masters.GetInstances() {
+				if master.ToHttpAddress() == key {
+					return true
+				}
+			}
+		}
+		if fs.filer != nil && fs.filer.MasterClient != nil {
+			if _, ok := fs.filer.MasterClient.ListMasterSet()[key]; ok {
+				return true
+			}
+		}
+		return false
+	}
+	return false
+}
+
 func (fs *FilerServer) Ping(ctx context.Context, req *filer_pb.PingRequest) (resp *filer_pb.PingResponse, pingErr error) {
 	resp = &filer_pb.PingResponse{
 		StartTimeNs: time.Now().UnixNano(),
 	}
+	// Empty target is a self-liveness probe and stays unauthenticated.
+	if req.Target != "" && !fs.isKnownPingTarget(ctx, req.Target, req.TargetType) {
+		resp.StopTimeNs = time.Now().UnixNano()
+		return resp, status.Errorf(codes.InvalidArgument, "unknown ping target %s of type %s", req.Target, req.TargetType)
+	}
 	if req.TargetType == cluster.FilerType {
 		pingErr = pb.WithFilerClient(false, 0, pb.ServerAddress(req.Target), fs.grpcDialOption, func(client filer_pb.SeaweedFilerClient) error {
 			pingResp, err := client.Ping(ctx, &filer_pb.PingRequest{})
diff --git a/weed/server/master_grpc_server_admin.go b/weed/server/master_grpc_server_admin.go
index ce90f5cac..a374c3530 100644
--- a/weed/server/master_grpc_server_admin.go
+++ b/weed/server/master_grpc_server_admin.go
@@ -15,6 +15,8 @@ import (
 	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
 	"github.com/seaweedfs/seaweedfs/weed/pb/volume_server_pb"
 	"github.com/seaweedfs/seaweedfs/weed/stats"
+	"google.golang.org/grpc/codes"
+	"google.golang.org/grpc/status"
 )
 
 /*
@@ -158,10 +160,42 @@ func (ms *MasterServer) ReleaseAdminToken(ctx context.Context, req *master_pb.Re
 	return resp, nil
 }
 
+// isKnownPingTarget reports whether target is a peer that the master has
+// learned about as part of cluster membership. Restricting Ping to known
+// peers avoids turning the RPC into a generic outbound dialer. The lookups
+// are O(1) so the gate stays cheap on clusters with thousands of nodes.
+func (ms *MasterServer) isKnownPingTarget(ctx context.Context, target string, targetType string) bool {
+	addr := pb.ServerAddress(target)
+	switch targetType {
+	case cluster.FilerType, cluster.BrokerType, cluster.S3Type:
+		return ms.Cluster.IsKnownNode(targetType, addr)
+	case cluster.VolumeServerType:
+		if ms.Topo == nil {
+			return false
+		}
+		return ms.Topo.LookupDataNodeByAddress(addr) != nil
+	case cluster.MasterType:
+		if ms.option != nil && ms.option.Master.Equals(addr) {
+			return true
+		}
+		if ms.MasterClient != nil {
+			_, ok := ms.MasterClient.ListMasterSet()[addr.ToHttpAddress()]
+			return ok
+		}
+		return false
+	}
+	return false
+}
+
 func (ms *MasterServer) Ping(ctx context.Context, req *master_pb.PingRequest) (resp *master_pb.PingResponse, pingErr error) {
 	resp = &master_pb.PingResponse{
 		StartTimeNs: time.Now().UnixNano(),
 	}
+	// Empty target is a self-liveness probe and stays unauthenticated.
+	if req.Target != "" && !ms.isKnownPingTarget(ctx, req.Target, req.TargetType) {
+		resp.StopTimeNs = time.Now().UnixNano()
+		return resp, status.Errorf(codes.InvalidArgument, "unknown ping target %s of type %s", req.Target, req.TargetType)
+	}
 	if req.TargetType == cluster.FilerType {
 		pingErr = pb.WithFilerClient(false, 0, pb.ServerAddress(req.Target), ms.grpcDialOption, func(client filer_pb.SeaweedFilerClient) error {
 			pingResp, err := client.Ping(ctx, &filer_pb.PingRequest{})
diff --git a/weed/server/master_grpc_server_admin_ping_test.go b/weed/server/master_grpc_server_admin_ping_test.go
new file mode 100644
index 000000000..5c8de4325
--- /dev/null
+++ b/weed/server/master_grpc_server_admin_ping_test.go
@@ -0,0 +1,97 @@
+package weed_server
+
+import (
+	"context"
+	"testing"
+
+	"github.com/seaweedfs/seaweedfs/weed/cluster"
+	"github.com/seaweedfs/seaweedfs/weed/pb"
+	"github.com/seaweedfs/seaweedfs/weed/sequence"
+	"github.com/seaweedfs/seaweedfs/weed/topology"
+)
+
+func TestMasterIsKnownPingTarget(t *testing.T) {
+	topo := topology.NewTopology("test", sequence.NewMemorySequencer(), 32*1024, 5, false)
+	dc := topology.NewDataCenter("dc1")
+	topo.LinkChildNode(dc)
+	rack := topology.NewRack("rack1")
+	dc.LinkChildNode(rack)
+
+	dn := topology.NewDataNode("vol1")
+	dn.Ip = "10.0.0.10"
+	dn.Port = 8080
+	dn.GrpcPort = 18080
+	rack.LinkChildNode(dn)
+
+	c := cluster.NewCluster()
+	filerAddr := pb.ServerAddress("10.0.0.20:8888")
+	c.AddClusterNode("", cluster.FilerType, "dc1", "rack1", filerAddr, "test")
+
+	ms := &MasterServer{
+		option:  &MasterOption{Master: pb.ServerAddress("10.0.0.1:9333")},
+		Topo:    topo,
+		Cluster: c,
+	}
+
+	ctx := context.Background()
+	cases := []struct {
+		name       string
+		target     string
+		targetType string
+		want       bool
+	}{
+		{"known filer", string(filerAddr), cluster.FilerType, true},
+		{"known volume server", "10.0.0.10:8080.18080", cluster.VolumeServerType, true},
+		{"known volume server http addr", "10.0.0.10:8080", cluster.VolumeServerType, true},
+		{"known self master", "10.0.0.1:9333", cluster.MasterType, true},
+		{"unknown localhost low port", "127.0.0.1:1", cluster.VolumeServerType, false},
+		{"unknown localhost high port", "127.0.0.1:65000", cluster.FilerType, false},
+		{"unrelated host", "example.com:443", cluster.MasterType, false},
+		{"unknown target type", string(filerAddr), "garbage", false},
+		{"filer address checked as volume server", string(filerAddr), cluster.VolumeServerType, false},
+	}
+
+	for _, tc := range cases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			got := ms.isKnownPingTarget(ctx, tc.target, tc.targetType)
+			if got != tc.want {
+				t.Fatalf("isKnownPingTarget(%q,%q) = %v, want %v", tc.target, tc.targetType, got, tc.want)
+			}
+		})
+	}
+}
+
+func TestVolumeServerIsKnownPingTarget(t *testing.T) {
+	seed := pb.ServerAddress("10.0.0.1:9333")
+	vs := &VolumeServer{
+		SeedMasterNodes: []pb.ServerAddress{seed},
+		seedMasterSet:   map[string]struct{}{seed.ToHttpAddress(): {}},
+	}
+	vs.setCurrentMaster(pb.ServerAddress("10.0.0.2:9333"))
+
+	cases := []struct {
+		name       string
+		target     string
+		targetType string
+		want       bool
+	}{
+		{"seed master", string(seed), cluster.MasterType, true},
+		{"current master", "10.0.0.2:9333", cluster.MasterType, true},
+		{"other volume server", "10.0.0.5:8080", cluster.VolumeServerType, false},
+		{"random filer", "10.0.0.6:8888", cluster.FilerType, false},
+		{"unknown low port", "127.0.0.1:1", cluster.MasterType, false},
+		{"unknown high port", "127.0.0.1:65000", cluster.MasterType, false},
+		{"unrelated host", "example.com:443", cluster.MasterType, false},
+	}
+
+	for _, tc := range cases {
+		tc := tc
+		t.Run(tc.name, func(t *testing.T) {
+			got := vs.isKnownPingTarget(tc.target, tc.targetType)
+			if got != tc.want {
+				t.Fatalf("isKnownPingTarget(%q,%q) = %v, want %v", tc.target, tc.targetType, got, tc.want)
+			}
+		})
+	}
+}
diff --git a/weed/server/volume_grpc_admin.go b/weed/server/volume_grpc_admin.go
index 1ea290fc8..0d54d3160 100644
--- a/weed/server/volume_grpc_admin.go
+++ b/weed/server/volume_grpc_admin.go
@@ -447,10 +447,37 @@ func (vs *VolumeServer) VolumeNeedleStatus(ctx context.Context, req *volume_serv
 
 }
 
+// isKnownPingTarget reports whether target is a master this volume server
+// already knows about. Volume servers do not maintain a peer-volume or
+// peer-filer list, so Ping is scoped to the masters they heartbeat with.
+// The current-master read is taken under a lock to avoid racing with the
+// heartbeat goroutine that rewrites it on leader changes, and the seed
+// list is consulted via a pre-built set so the check stays O(1).
+func (vs *VolumeServer) isKnownPingTarget(target string, targetType string) bool {
+	if targetType != cluster.MasterType {
+		return false
+	}
+	addr := pb.ServerAddress(target)
+	key := addr.ToHttpAddress()
+	if key == "" {
+		return false
+	}
+	if current := vs.getCurrentMaster(); current != "" && current.ToHttpAddress() == key {
+		return true
+	}
+	_, ok := vs.seedMasterSet[key]
+	return ok
+}
+
 func (vs *VolumeServer) Ping(ctx context.Context, req *volume_server_pb.PingRequest) (resp *volume_server_pb.PingResponse, pingErr error) {
 	resp = &volume_server_pb.PingResponse{
 		StartTimeNs: time.Now().UnixNano(),
 	}
+	// Empty target is a self-liveness probe and stays unauthenticated.
+	if req.Target != "" && !vs.isKnownPingTarget(req.Target, req.TargetType) {
+		resp.StopTimeNs = time.Now().UnixNano()
+		return resp, status.Errorf(codes.InvalidArgument, "unknown ping target %s of type %s", req.Target, req.TargetType)
+	}
 	if req.TargetType == cluster.FilerType {
 		pingErr = pb.WithFilerClient(false, 0, pb.ServerAddress(req.Target), vs.grpcDialOption, func(client filer_pb.SeaweedFilerClient) error {
 			pingResp, err := client.Ping(ctx, &filer_pb.PingRequest{})
diff --git a/weed/server/volume_grpc_client_to_master.go b/weed/server/volume_grpc_client_to_master.go
index 6214711e4..f48fc51f7 100644
--- a/weed/server/volume_grpc_client_to_master.go
+++ b/weed/server/volume_grpc_client_to_master.go
@@ -24,9 +24,26 @@ import (
 )
 
 func (vs *VolumeServer) GetMaster(ctx context.Context) pb.ServerAddress {
+	return vs.getCurrentMaster()
+}
+
+// getCurrentMaster returns vs.currentMaster under a read lock so callers
+// (e.g. Ping admission) do not race with the heartbeat goroutine that
+// rewrites it on leader changes.
+func (vs *VolumeServer) getCurrentMaster() pb.ServerAddress {
+	vs.currentMasterLock.RLock()
+	defer vs.currentMasterLock.RUnlock()
 	return vs.currentMaster
 }
 
+// setCurrentMaster updates vs.currentMaster under a write lock. The
+// heartbeat goroutine calls this whenever it (re)connects to a master.
+func (vs *VolumeServer) setCurrentMaster(master pb.ServerAddress) {
+	vs.currentMasterLock.Lock()
+	vs.currentMaster = master
+	vs.currentMasterLock.Unlock()
+}
+
 func (vs *VolumeServer) checkWithMaster() (err error) {
 	for {
 		for _, master := range vs.SeedMasterNodes {
@@ -126,7 +143,7 @@ func (vs *VolumeServer) doHeartbeatWithRetry(masterAddress pb.ServerAddress, grp
 		return "", err
 	}
 	glog.V(0).Infof("Heartbeat to: %v", masterAddress)
-	vs.currentMaster = masterAddress
+	vs.setCurrentMaster(masterAddress)
 
 	doneChan := make(chan error, 1)
 
@@ -176,16 +193,19 @@ func (vs *VolumeServer) doHeartbeatWithRetry(masterAddress pb.ServerAddress, grp
 			if volumeOptsChanged {
 				if vs.store.MaybeAdjustVolumeMax() {
 					if err = stream.Send(vs.store.CollectHeartbeat()); err != nil {
-						glog.V(0).Infof("Volume Server Failed to talk with master %s: %v", vs.currentMaster, err)
+						glog.V(0).Infof("Volume Server Failed to talk with master %s: %v", vs.getCurrentMaster(), err)
 						return
 					}
 				}
 			}
-			if in.GetLeader() != "" && !vs.currentMaster.Equals(pb.ServerAddress(in.GetLeader())) {
-				glog.V(0).Infof("Volume Server found a new master newLeader: %v instead of %v", in.GetLeader(), vs.currentMaster)
-				newLeader = pb.ServerAddress(in.GetLeader())
-				doneChan <- nil
-				return
+			if in.GetLeader() != "" {
+				current := vs.getCurrentMaster()
+				if !current.Equals(pb.ServerAddress(in.GetLeader())) {
+					glog.V(0).Infof("Volume Server found a new master newLeader: %v instead of %v", in.GetLeader(), current)
+					newLeader = pb.ServerAddress(in.GetLeader())
+					doneChan <- nil
+					return
+				}
 			}
 		}
 	}()
diff --git a/weed/server/volume_server.go b/weed/server/volume_server.go
index 974156e28..d53d2919a 100644
--- a/weed/server/volume_server.go
+++ b/weed/server/volume_server.go
@@ -34,9 +34,14 @@ type VolumeServer struct {
 	readBufferSizeMB              int
 
 	SeedMasterNodes []pb.ServerAddress
-	whiteList       []string
-	currentMaster   pb.ServerAddress
-	pulsePeriod     time.Duration
+	// seedMasterSet mirrors SeedMasterNodes keyed by the canonical http
+	// form. It is computed once in NewVolumeServer so admission paths can
+	// answer is-this-a-seed-master in O(1).
+	seedMasterSet     map[string]struct{}
+	whiteList         []string
+	currentMaster     pb.ServerAddress
+	currentMasterLock sync.RWMutex
+	pulsePeriod       time.Duration
 	dataCenter      string
 	rack            string
 	store           *storage.Store
@@ -117,7 +122,15 @@ func NewVolumeServer(adminMux, publicMux *http.ServeMux, ip string,
 	}
 
 	whiteList = append(whiteList, util.StringSplit(v.GetString("guard.white_list"), ",")...)
-	vs.SeedMasterNodes = masterNodes
+	// Copy the caller's slice so subsequent external mutation cannot desync
+	// SeedMasterNodes from the frozen lookup set built below.
+	seedMasters := make([]pb.ServerAddress, len(masterNodes))
+	copy(seedMasters, masterNodes)
+	vs.SeedMasterNodes = seedMasters
+	vs.seedMasterSet = make(map[string]struct{}, len(seedMasters))
+	for _, m := range seedMasters {
+		vs.seedMasterSet[m.ToHttpAddress()] = struct{}{}
+	}
 
 	vs.checkWithMaster()
 
diff --git a/weed/shell/command_cluster_check.go b/weed/shell/command_cluster_check.go
index 4a1460e27..86c58ff71 100644
--- a/weed/shell/command_cluster_check.go
+++ b/weed/shell/command_cluster_check.go
@@ -213,28 +213,11 @@ func (c *commandClusterCheck) Do(args []string, commandEnv *CommandEnv, writer i
 		}
 	}
 
-	// check between volume servers
-	for _, sourceVolumeServer := range volumeServers {
-		for _, targetVolumeServer := range volumeServers {
-			if sourceVolumeServer == targetVolumeServer {
-				continue
-			}
-			fmt.Fprintf(writer, "checking volume server %s to %s ... ", string(sourceVolumeServer), string(targetVolumeServer))
-			err := pb.WithVolumeServerClient(false, sourceVolumeServer, commandEnv.option.GrpcDialOption, func(client volume_server_pb.VolumeServerClient) error {
-				pong, err := client.Ping(context.Background(), &volume_server_pb.PingRequest{
-					Target:     string(targetVolumeServer),
-					TargetType: cluster.VolumeServerType,
-				})
-				if err == nil {
-					printTiming(writer, pong.StartTimeNs, pong.RemoteTimeNs, pong.StopTimeNs)
-				}
-				return err
-			})
-			if err != nil {
-				fmt.Fprintf(writer, "%v\n", err)
-			}
-		}
-	}
+	// Direct volume-to-volume connectivity is intentionally not validated
+	// here. Each volume server now restricts Ping to peers it can identify
+	// (its configured/current masters), so it does not carry a peer-volume
+	// list to drive a mesh check from. The master->volume and filer->volume
+	// probes above do not exercise volume-to-volume reachability.
 
 	// check between filers, and need to connect to itself
 	for _, sourceFiler := range filers {
diff --git a/weed/topology/node.go b/weed/topology/node.go
index 3a11d0433..f6073326f 100644
--- a/weed/topology/node.go
+++ b/weed/topology/node.go
@@ -424,6 +424,13 @@ func (n *NodeImpl) doLinkChildNode(node Node) {
 		}
 		n.UpAdjustMaxVolumeId(node.GetMaxVolumeId())
 		node.SetParent(n)
+		// Maintain the topology's address index so Ping admission and other
+		// callers can resolve a data node from its address in O(1).
+		if dn, ok := node.GetValue().(*DataNode); ok {
+			if topo := n.GetTopology(); topo != nil {
+				topo.registerDataNodeAddress(dn)
+			}
+		}
 		glog.V(0).Infoln(n, "adds child", node.Id())
 	}
 }
@@ -433,6 +440,13 @@ func (n *NodeImpl) UnlinkChildNode(nodeId NodeId) {
 	defer n.Unlock()
 	node := n.children[nodeId]
 	if node != nil {
+		// Drop the topology address index before clearing the parent pointer
+		// so GetTopology() can still walk up to the root.
+		if dn, ok := node.GetValue().(*DataNode); ok {
+			if topo := n.GetTopology(); topo != nil {
+				topo.unregisterDataNodeAddress(dn.ServerAddress(), dn)
+			}
+		}
 		node.SetParent(nil)
 		delete(n.children, node.Id())
 		for dt, du := range node.GetDiskUsages().negative().usages {
@@ -484,10 +498,13 @@ func (n *NodeImpl) CollectDeadNodeAndFullVolumes(freshThreshHoldUnixTime int64,
 }
 
 func (n *NodeImpl) GetTopology() *Topology {
-	var p Node
-	p = n
+	var p Node = n
 	for p.Parent() != nil {
 		p = p.Parent()
 	}
-	return p.GetValue().(*Topology)
+	// A detached subtree (no Topology root in scope) must not panic; the
+	// callers above check the returned value for nil and skip the
+	// address-index maintenance in that case.
+	topo, _ := p.GetValue().(*Topology)
+	return topo
 }
diff --git a/weed/topology/rack.go b/weed/topology/rack.go
index 1e5c8b632..4facd30f6 100644
--- a/weed/topology/rack.go
+++ b/weed/topology/rack.go
@@ -6,6 +6,7 @@ import (
 	"time"
 
 	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/pb"
 	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
 	"github.com/seaweedfs/seaweedfs/weed/storage/types"
 	"github.com/seaweedfs/seaweedfs/weed/util"
@@ -60,7 +61,10 @@ func (r *Rack) GetOrCreateDataNode(ip string, port int, grpcPort int, publicUrl
 	if c, ok := r.children[NodeId(nodeId)]; ok {
 		dn := c.(*DataNode)
 		// Log if IP or Port changed (e.g., pod rescheduled in K8s)
-		if dn.Ip != ip || dn.Port != port {
+		addrChanged := dn.Ip != ip || dn.Port != port
+		var oldAddr pb.ServerAddress
+		if addrChanged {
+			oldAddr = dn.ServerAddress()
 			glog.V(0).Infof("DataNode %s address changed from %s:%d to %s:%d", nodeId, dn.Ip, dn.Port, ip, port)
 		}
 		// Update the IP/Port in case they changed
@@ -69,6 +73,12 @@ func (r *Rack) GetOrCreateDataNode(ip string, port int, grpcPort int, publicUrl
 		dn.GrpcPort = grpcPort
 		dn.PublicUrl = publicUrl
 		dn.LastSeen = time.Now().Unix()
+		if addrChanged {
+			if topo := r.GetTopology(); topo != nil {
+				topo.unregisterDataNodeAddress(oldAddr, dn)
+				topo.registerDataNodeAddress(dn)
+			}
+		}
 		return dn
 	}
 
@@ -92,7 +102,8 @@ func (r *Rack) GetOrCreateDataNode(ip string, port int, grpcPort int, publicUrl
 				delete(r.children, oldId)
 				dn.id = NodeId(nodeId)
 				r.children[NodeId(nodeId)] = dn
-				// Update connection info in case they changed
+				// Update connection info in case they changed; address itself is
+				// unchanged on legacy transition, so the index entry stays valid.
 				dn.GrpcPort = grpcPort
 				dn.PublicUrl = publicUrl
 				dn.LastSeen = time.Now().Unix()
diff --git a/weed/topology/topology.go b/weed/topology/topology.go
index 5c779f343..b99bbd816 100644
--- a/weed/topology/topology.go
+++ b/weed/topology/topology.go
@@ -73,6 +73,14 @@ type Topology struct {
 	lastLeaderChangeTime     time.Time
 	hadVolumesAtLeaderChange bool
 	lastLeaderChangeTimeLock sync.RWMutex
+
+	// dataNodeIndex is an address -> *DataNode lookup so callers (e.g. the
+	// Ping admission gate) do not have to walk every dc/rack/node tier on
+	// every request. Keys use the canonical http form returned by
+	// pb.ServerAddress.ToHttpAddress so a target like "1.2.3.4:8080" finds
+	// the same node whether or not the grpc port suffix is present.
+	dataNodeIndex     map[string]*DataNode
+	dataNodeIndexLock sync.RWMutex
 }
 
 func NewTopology(id string, seq sequence.Sequencer, volumeSizeLimit uint64, pulse int, replicationAsMin bool) *Topology {
@@ -95,10 +103,65 @@ func NewTopology(id string, seq sequence.Sequencer, volumeSizeLimit uint64, puls
 	t.chanCrowdedVolumes = make(chan storage.VolumeInfo)
 
 	t.Configuration = &Configuration{}
+	t.dataNodeIndex = make(map[string]*DataNode)
 
 	return t
 }
 
+// LookupDataNodeByAddress returns the registered DataNode that serves addr,
+// or nil if no such node has been observed. Lookup is O(1) and uses the
+// canonical http form of the address so callers that pass either
+// "host:port" or "host:port.grpc" find the same node.
+func (t *Topology) LookupDataNodeByAddress(addr pb.ServerAddress) *DataNode {
+	if addr == "" {
+		return nil
+	}
+	t.dataNodeIndexLock.RLock()
+	defer t.dataNodeIndexLock.RUnlock()
+	if t.dataNodeIndex == nil {
+		return nil
+	}
+	return t.dataNodeIndex[addr.ToHttpAddress()]
+}
+
+// registerDataNodeAddress records dn in the address index under its current
+// http address. Callers must invoke unregisterDataNodeAddress with the prior
+// address whenever a node's Ip or Port changes (e.g. k8s pod reschedule).
+func (t *Topology) registerDataNodeAddress(dn *DataNode) {
+	if dn == nil {
+		return
+	}
+	key := dn.ServerAddress().ToHttpAddress()
+	if key == "" {
+		return
+	}
+	t.dataNodeIndexLock.Lock()
+	defer t.dataNodeIndexLock.Unlock()
+	if t.dataNodeIndex == nil {
+		t.dataNodeIndex = make(map[string]*DataNode)
+	}
+	t.dataNodeIndex[key] = dn
+}
+
+// unregisterDataNodeAddress removes the index entry for addr, but only when
+// the entry still points at dn. The conditional guard avoids dropping a
+// freshly re-registered node whose address happens to alias the one being
+// removed (e.g. legacy id transitions or a fast restart).
+func (t *Topology) unregisterDataNodeAddress(addr pb.ServerAddress, dn *DataNode) {
+	if addr == "" {
+		return
+	}
+	key := addr.ToHttpAddress()
+	if key == "" {
+		return
+	}
+	t.dataNodeIndexLock.Lock()
+	defer t.dataNodeIndexLock.Unlock()
+	if existing, ok := t.dataNodeIndex[key]; ok && (dn == nil || existing == dn) {
+		delete(t.dataNodeIndex, key)
+	}
+}
+
 func (t *Topology) IsChildLocked() (bool, error) {
 	if t.IsLocked() {
 		return true, errors.New("topology is locked")
diff --git a/weed/topology/topology_event_handling.go b/weed/topology/topology_event_handling.go
index 739136199..8772ecb89 100644
--- a/weed/topology/topology_event_handling.go
+++ b/weed/topology/topology_event_handling.go
@@ -108,6 +108,7 @@ func (t *Topology) UnRegisterDataNode(dn *DataNode) {
 	}
 	dn.DeltaUpdateVolumes([]storage.VolumeInfo{}, dn.GetVolumes())
 	dn.DeltaUpdateEcShards([]*erasure_coding.EcVolumeInfo{}, dn.GetEcShards())
+	t.unregisterDataNodeAddress(dn.ServerAddress(), dn)
 	if dn.Parent() != nil {
 		dn.Parent().UnlinkChildNode(dn.Id())
 	}
diff --git a/weed/topology/topology_test.go b/weed/topology/topology_test.go
index 5885bbbb4..415a7198d 100644
--- a/weed/topology/topology_test.go
+++ b/weed/topology/topology_test.go
@@ -3,6 +3,7 @@ package topology
 import (
 	"reflect"
 
+	"github.com/seaweedfs/seaweedfs/weed/pb"
 	"github.com/seaweedfs/seaweedfs/weed/pb/master_pb"
 	"github.com/seaweedfs/seaweedfs/weed/sequence"
 	"github.com/seaweedfs/seaweedfs/weed/storage"
@@ -530,3 +531,45 @@ func TestDataNodeIdBasedIdentification(t *testing.T) {
 		t.Errorf("expected 4 DataNodes, got %d", len(children))
 	}
 }
+
+func TestLookupDataNodeByAddress(t *testing.T) {
+	topo := NewTopology("weedfs", sequence.NewMemorySequencer(), 32*1024, 5, false)
+	dc := topo.GetOrCreateDataCenter("dc1")
+	rack := dc.GetOrCreateRack("rack1")
+
+	maxVolumeCounts := map[string]uint32{"": 10}
+
+	// Brand-new registration must be discoverable by both the http and
+	// grpc forms of the address.
+	dn := rack.GetOrCreateDataNode("10.1.2.3", 8080, 18080, "10.1.2.3:8080", "n1", maxVolumeCounts)
+	if got := topo.LookupDataNodeByAddress(pb.ServerAddress("10.1.2.3:8080")); got != dn {
+		t.Fatalf("lookup by http address: got %v, want %v", got, dn)
+	}
+	if got := topo.LookupDataNodeByAddress(pb.ServerAddress("10.1.2.3:8080.18080")); got != dn {
+		t.Fatalf("lookup by grpc-suffix address: got %v, want %v", got, dn)
+	}
+
+	// Unknown addresses must miss.
+	if got := topo.LookupDataNodeByAddress(pb.ServerAddress("127.0.0.1:1")); got != nil {
+		t.Fatalf("unknown address must not be found, got %v", got)
+	}
+
+	// Heartbeat from a moved pod (same id, new ip) updates the index in
+	// place: the old address is dropped and the new one resolves.
+	dnMoved := rack.GetOrCreateDataNode("10.9.9.9", 8080, 18080, "10.9.9.9:8080", "n1", maxVolumeCounts)
+	if dnMoved != dn {
+		t.Fatalf("expected same node instance after move, got different")
+	}
+	if got := topo.LookupDataNodeByAddress(pb.ServerAddress("10.1.2.3:8080")); got != nil {
+		t.Fatalf("old address must be unregistered after move, got %v", got)
+	}
+	if got := topo.LookupDataNodeByAddress(pb.ServerAddress("10.9.9.9:8080")); got != dn {
+		t.Fatalf("new address lookup: got %v, want %v", got, dn)
+	}
+
+	// UnRegisterDataNode evicts the index entry.
+	topo.UnRegisterDataNode(dn)
+	if got := topo.LookupDataNodeByAddress(pb.ServerAddress("10.9.9.9:8080")); got != nil {
+		t.Fatalf("address must be unregistered after UnRegisterDataNode, got %v", got)
+	}
+}
diff --git a/weed/wdclient/masterclient.go b/weed/wdclient/masterclient.go
index 3070019c1..4dd3a86a4 100644
--- a/weed/wdclient/masterclient.go
+++ b/weed/wdclient/masterclient.go
@@ -439,6 +439,18 @@ func (mc *MasterClient) GetMasters(ctx context.Context) []pb.ServerAddress {
 	return mc.masters.GetInstances()
 }
 
+// ListMasterSet returns a set of configured master addresses keyed by their
+// canonical http form. Unlike GetMasters this does not wait for a connection,
+// so it is safe to call from admission paths that must stay non-blocking.
+func (mc *MasterClient) ListMasterSet() map[string]struct{} {
+	addrs := mc.masters.GetInstances()
+	set := make(map[string]struct{}, len(addrs))
+	for _, a := range addrs {
+		set[a.ToHttpAddress()] = struct{}{}
+	}
+	return set
+}
+
 // WaitUntilConnected blocks until a master connection is established or ctx is canceled.
 // This does NOT initiate connections - it only waits for KeepConnectedToMaster to succeed.
 func (mc *MasterClient) WaitUntilConnected(ctx context.Context) {
diff --git a/weed/wdclient/vid_map.go b/weed/wdclient/vid_map.go
index e3acaf81a..de5b09de1 100644
--- a/weed/wdclient/vid_map.go
+++ b/weed/wdclient/vid_map.go
@@ -36,18 +36,32 @@ type vidMap struct {
 	sync.RWMutex
 	vid2Locations   map[uint32][]Location
 	ecVid2Locations map[uint32][]Location
-	DataCenter      string
-	cache           atomic.Pointer[vidMap]
+	// serverRefCount tracks how many vid locations (regular + EC) currently
+	// reference each volume server address. Maintaining it incrementally lets
+	// hasVolumeServer answer in O(1) instead of walking every volume entry.
+	// Keys are the canonical http form of pb.ServerAddress, so callers that
+	// pass either "host:port" or "host:port.grpc" find the same entry.
+	serverRefCount map[string]int
+	DataCenter     string
+	cache          atomic.Pointer[vidMap]
 }
 
 func newVidMap(dataCenter string) *vidMap {
 	return &vidMap{
 		vid2Locations:   make(map[uint32][]Location),
 		ecVid2Locations: make(map[uint32][]Location),
+		serverRefCount:  make(map[string]int),
 		DataCenter:      dataCenter,
 	}
 }
 
+// locationServerKey returns the index key used by serverRefCount for a
+// Location. The key normalises away the optional grpc-port suffix so the
+// counter stays consistent with hasVolumeServer's lookup.
+func locationServerKey(loc Location) string {
+	return loc.ServerAddress().ToHttpAddress()
+}
+
 func (vc *vidMap) isSameDataCenter(loc *Location) bool {
 	if vc.DataCenter == "" || loc.DataCenter == "" || vc.DataCenter != loc.DataCenter {
 		return false
@@ -152,6 +166,28 @@ func (vc *vidMap) getLocations(vid uint32) (locations []Location, found bool) {
 	return
 }
 
+// hasVolumeServer reports whether any tracked volume (regular or EC) is hosted
+// on addr. It walks the cache chain so recently expired maps are still
+// considered. Used to gate admission of operations targeting a volume server.
+// The lookup is O(1) thanks to serverRefCount; we still consult the cache
+// chain to keep covering volume servers that just rolled out of the live map.
+func (vc *vidMap) hasVolumeServer(addr pb.ServerAddress) bool {
+	key := addr.ToHttpAddress()
+	if key == "" {
+		return false
+	}
+	vc.RLock()
+	count := vc.serverRefCount[key]
+	vc.RUnlock()
+	if count > 0 {
+		return true
+	}
+	if cachedMap := vc.cache.Load(); cachedMap != nil {
+		return cachedMap.hasVolumeServer(addr)
+	}
+	return false
+}
+
 func (vc *vidMap) addLocation(vid uint32, location Location) {
 	vc.Lock()
 	defer vc.Unlock()
@@ -161,6 +197,7 @@ func (vc *vidMap) addLocation(vid uint32, location Location) {
 	locations, found := vc.vid2Locations[vid]
 	if !found {
 		vc.vid2Locations[vid] = []Location{location}
+		vc.incrementServerRef(locationServerKey(location))
 		return
 	}
 
@@ -171,6 +208,7 @@ func (vc *vidMap) addLocation(vid uint32, location Location) {
 	}
 
 	vc.vid2Locations[vid] = append(locations, location)
+	vc.incrementServerRef(locationServerKey(location))
 
 }
 
@@ -183,6 +221,7 @@ func (vc *vidMap) addEcLocation(vid uint32, location Location) {
 	locations, found := vc.ecVid2Locations[vid]
 	if !found {
 		vc.ecVid2Locations[vid] = []Location{location}
+		vc.incrementServerRef(locationServerKey(location))
 		return
 	}
 
@@ -193,6 +232,7 @@ func (vc *vidMap) addEcLocation(vid uint32, location Location) {
 	}
 
 	vc.ecVid2Locations[vid] = append(locations, location)
+	vc.incrementServerRef(locationServerKey(location))
 
 }
 
@@ -214,6 +254,7 @@ func (vc *vidMap) deleteLocation(vid uint32, location Location) {
 	for i, loc := range locations {
 		if loc.Url == location.Url {
 			vc.vid2Locations[vid] = append(locations[0:i], locations[i+1:]...)
+			vc.decrementServerRef(locationServerKey(loc))
 			break
 		}
 	}
@@ -237,6 +278,7 @@ func (vc *vidMap) deleteEcLocation(vid uint32, location Location) {
 	for i, loc := range locations {
 		if loc.Url == location.Url {
 			vc.ecVid2Locations[vid] = append(locations[0:i], locations[i+1:]...)
+			vc.decrementServerRef(locationServerKey(loc))
 			break
 		}
 	}
@@ -250,6 +292,38 @@ func (vc *vidMap) deleteVid(vid uint32) {
 	vc.Lock()
 	defer vc.Unlock()
 
+	for _, loc := range vc.vid2Locations[vid] {
+		vc.decrementServerRef(locationServerKey(loc))
+	}
+	for _, loc := range vc.ecVid2Locations[vid] {
+		vc.decrementServerRef(locationServerKey(loc))
+	}
 	delete(vc.vid2Locations, vid)
 	delete(vc.ecVid2Locations, vid)
 }
+
+// incrementServerRef increases the refcount for key. Empty keys are skipped
+// so a zero-value Location (which serialises to "") does not leak a permanent
+// bucket that hasVolumeServer and decrementServerRef both ignore. Callers
+// must hold vc's write lock.
+func (vc *vidMap) incrementServerRef(key string) {
+	if key == "" {
+		return
+	}
+	vc.serverRefCount[key]++
+}
+
+// decrementServerRef decreases the refcount for key and removes the entry
+// once it falls to zero. Callers must hold vc's write lock.
+func (vc *vidMap) decrementServerRef(key string) {
+	if key == "" {
+		return
+	}
+	if n, ok := vc.serverRefCount[key]; ok {
+		if n <= 1 {
+			delete(vc.serverRefCount, key)
+		} else {
+			vc.serverRefCount[key] = n - 1
+		}
+	}
+}
diff --git a/weed/wdclient/vid_map_test.go b/weed/wdclient/vid_map_test.go
index ec0aa86e9..161c0cfe0 100644
--- a/weed/wdclient/vid_map_test.go
+++ b/weed/wdclient/vid_map_test.go
@@ -117,3 +117,50 @@ func TestConcurrentGetLocations(t *testing.T) {
 	cancel()
 	wg.Wait()
 }
+
+func TestHasVolumeServer(t *testing.T) {
+	mc := NewMasterClient(grpc.EmptyDialOption{}, "", "", "", "", "", pb.ServerDiscovery{})
+
+	regular := Location{Url: "10.0.0.1:8080", GrpcPort: 18080}
+	ecOnly := Location{Url: "10.0.0.2:8080", GrpcPort: 18080}
+
+	mc.addLocation(7, regular)
+	mc.addEcLocation(9, ecOnly)
+
+	addr := func(u string) pb.ServerAddress { return pb.ServerAddress(u) }
+
+	if !mc.HasVolumeServer(addr("10.0.0.1:8080")) {
+		t.Fatalf("regular volume server must be known by http address")
+	}
+	if !mc.HasVolumeServer(addr("10.0.0.1:8080.18080")) {
+		t.Fatalf("regular volume server must be known by grpc-suffix address")
+	}
+	if !mc.HasVolumeServer(addr("10.0.0.2:8080")) {
+		t.Fatalf("ec-only volume server must be known")
+	}
+	if mc.HasVolumeServer(addr("127.0.0.1:1")) {
+		t.Fatalf("unknown address must not be known")
+	}
+
+	// Adding the same location twice must not double-count:
+	// deleting once should evict the server.
+	mc.addLocation(7, regular)
+	mc.deleteLocation(7, regular)
+	if mc.HasVolumeServer(addr("10.0.0.1:8080")) {
+		t.Fatalf("server should be evicted after deleteLocation")
+	}
+
+	// Removing the EC entry must also drop the index entry.
+	mc.deleteEcLocation(9, ecOnly)
+	if mc.HasVolumeServer(addr("10.0.0.2:8080")) {
+		t.Fatalf("server should be evicted after deleteEcLocation")
+	}
+
+	// deleteVid removes every reference held by that vid in one call.
+	mc.addLocation(11, regular)
+	mc.addEcLocation(11, regular)
+	mc.InvalidateCache("11,abc")
+	if mc.HasVolumeServer(addr("10.0.0.1:8080")) {
+		t.Fatalf("server should be evicted after InvalidateCache")
+	}
+}
diff --git a/weed/wdclient/vidmap_client.go b/weed/wdclient/vidmap_client.go
index 579291bfc..9636f8991 100644
--- a/weed/wdclient/vidmap_client.go
+++ b/weed/wdclient/vidmap_client.go
@@ -13,6 +13,7 @@ import (
 	"golang.org/x/sync/singleflight"
 
 	"github.com/seaweedfs/seaweedfs/weed/glog"
+	"github.com/seaweedfs/seaweedfs/weed/pb"
 )
 
 // VolumeLocationProvider is the interface for looking up volume locations
@@ -290,6 +291,13 @@ func (vc *vidMapClient) LookupVolumeServerUrl(vid string) (serverUrls []string,
 	return vc.getStableVidMap().LookupVolumeServerUrl(vid)
 }
 
+// HasVolumeServer reports whether addr is currently a known volume server
+// (hosts at least one volume or EC shard) in the cached vid map. Used by
+// admission paths that must only contact peers learned from the master.
+func (vc *vidMapClient) HasVolumeServer(addr pb.ServerAddress) bool {
+	return vc.getStableVidMap().hasVolumeServer(addr)
+}
+
 // GetDataCenter safely retrieves the data center
 func (vc *vidMapClient) GetDataCenter() string {
 	return vc.getStableVidMap().DataCenter