Client-Server Connectivity

Client-server connectivity issues occur when an application client is unable to connect to an NCache cache server or when cache operations fail due to communication, configuration, security, or service availability problems. These issues can prevent applications from performing cache operations such as add, insert, get, remove, query, or pub/sub messaging.

This page explains how to diagnose common client-server connectivity issues by validating cache status, client node configuration, network access, port availability, security settings, service health, and client-side logs.

Common Symptoms

You may have a client-server connectivity issue if you observe any of the following:

  • The client application cannot connect to the cache.
  • Cache operations fail with connection-related exceptions.
  • The client node does not appear connected in the NCache Management Center.
  • The cache is running, but application requests are not reaching the cache server.
  • Test-Stress fails from the client machine.
  • Client requests, requests/sec, or connection counters do not update.
  • Errors appear in client logs, server logs, or Windows/Linux event logs.

Step 1: Verify Cache and Service Status

First, confirm that the cache is created and running on the intended cache servers. If the cache is stopped, client applications cannot perform operations against it.

Also verify that the NCache Service is running on the server node. The NCache Service manages cache runtime, client connections, and management operations on the server.

You can check cache and service status using:

  • NCache Management Center
  • PowerShell cmdlets
  • NCache logs
  • Windows Services or Linux system service commands

Step 2: Verify Client Node Configuration

Make sure the application machine is added as a client node for the target cache. If the client node is not registered, the application may not have the required client configuration to locate and connect to cache servers.

Check the following:

  • The client node is added to the correct cache.
  • The client node IP or machine name is correct.
  • The client configuration contains the correct cache name.
  • The client configuration contains reachable server IPs or hostnames.
  • The client node can resolve server names if hostnames are used.

If the client configuration is incorrect, update it through the NCache Management Center or by editing the relevant configuration file.

Step 3: Verify Network Connectivity

The client machine must be able to reach the cache server over the required NCache ports. Network-level issues are a common cause of client-server connectivity failures.

Check the following:

  • The client and server are on reachable networks.
  • Firewall rules allow NCache communication.
  • Required ports are open.
  • No network policy, VPN rule, or security group is blocking traffic.
  • The client can reach the server IP or hostname.
  • The server is listening on the expected client-server communication port.

On Windows, you can test basic port connectivity using:

Test-NetConnection <server-ip> -Port <port>

On Linux, you can use:

nc -vz <server-ip> <port>

If the port test fails, review firewall, routing, IP binding, and network security rules.

Step 4: Check IP Binding and Multi-NIC Configuration

If the server has multiple Network Interface Cards, the client may be trying to connect through an IP address that NCache is not bound to. In multi-NIC environments, verify that NCache is configured to use the correct IP address for client-server communication.

Check the following:

  • The client is connecting to the IP assigned for client-server communication.
  • BindToClientServerIP is configured correctly.
  • The selected IP is reachable from the client machine.
  • The server is not advertising an internal or unreachable IP to clients.
  • Any server mapping is correctly configured if clients and servers are on different networks.

Incorrect IP binding can cause a cache server to be running but unreachable from client applications.

Step 5: Validate Security Configuration

If security is enabled, connection failures may occur because of missing, incorrect, or unauthorized credentials.

Check the following:

  • The client application is using valid cache credentials.
  • The user has permission to access the cache.
  • The same security settings are applied consistently across the environment.
  • Credentials are correctly configured in the application or client configuration.
  • If TLS is enabled, the required certificates are installed and trusted.

Security-related failures are usually visible in client logs, server logs, or event logs.

Step 6: Run Test-Stress from the Client Machine

After validating configuration and network connectivity, run Test-Stress from the client machine to confirm that the client can connect to the cache and perform cache operations.

If Test-Stress runs successfully, the client-server connection is active and cache operations are being processed. You can also monitor cache counters such as requests/sec, additions/sec, fetches/sec, and client connections to confirm activity.

If Test-Stress fails, review the error message and continue checking logs, ports, IP binding, and security configuration.

Step 7: Review Logs and Event Information

Logs provide the most useful details when diagnosing connectivity issues. Review both client-side and server-side logs to identify the exact failure point.

Check the following:

  • Client logs for connection failures or timeout errors.
  • Server logs for rejected connections, service issues, or cache errors.
  • Event logs for service failures, node communication issues, or security errors.
  • NCache Management Center alerts or monitoring counters.
  • Trace events, if deeper diagnostics are required.

Use the timestamp of the failed connection attempt to correlate entries across client logs, server logs, and event logs.

Step 8: Verify Client Application Configuration

If the cache is reachable through tools but the application still fails, review the application configuration.

Check the following:

  • The application is using the correct cache name.
  • The correct NCache client libraries are referenced.
  • The application is using the expected client configuration file.
  • The application is running under an identity that has access to required configuration, certificates, and network resources.
  • The application is not overriding server or security settings at runtime.

Application-level configuration mismatches can appear as connectivity issues even when the cache and network are working correctly.

See Also

Connect To Cache
Add Client Node
Remove Client Node
Logging
Trace Events