How to Troubleshoot Application Connectivity Problems
Sometimes, you might be able to access the network with some applications but not others. For example, you might be able to download your e-mail but not access Web servers. Or, you might be able to view pages on a remote Web server but not connect to the computer with Remote Desktop.
Several issues might cause these symptoms (in rough order of likelihood):
- The remote service is not running. For example, Remote Desktop might not be enabled on the remote computer.
- The remote server has a firewall configured that is blocking that application's communications from your client computer.
- A firewall between the client and server computer is blocking that application's communications.
- Windows Firewall on the local computer might be configured to block the application's traffic.
- The remote service has been configured to use a non-default port number. For example, Web servers typically use TCP port 80, but some administrators might configure TCP port 81 or a different port.
To troubleshoot an application connectivity problem, follow these steps:
- Before you begin troubleshooting application connectivity, first verify that you do not
have a name resolution problem. To do this, open a command prompt and run the
command Nslookup servername. If Nslookup does not display an answer similar to
the following example, you have a name resolution problem. See the section titled
"How to Troubleshoot Name Resolution Problems" later in this tutorial.
Non-authoritative answer: Name: sourcedaddy.com Addresses: 220.127.116.11
- Identify the port number used by the application.
Table next section lists port numbers for common applications.
In this tutorial:
- Troubleshooting Network Issues
- Tools for Troubleshooting
- Table-1 Network Troubleshooting Tools
- How to Identify a Problem with the ARP Cacher
- How to Clear the ARP Cache
- Event Viewer
- How to View Shared Folders on the Local Computer
- How to View Shared Folders on Another Computer
- Network Monitor
- Verifying that the Default DNS Server Resolves Correctly
- Verifying that a Specific DNS Server Resolves Correctly
- Verifying Specific Types of Addresses
- Using TCP for DNS Lookups
- PathPing Output
- Routing Loops
- Performance Problems
- Possible Connectivity Issues
- No Connectivity Issues
- Performance Monitor
- Data Collector Sets
- Windows Resource Monitor
- Identifying the TCP Port for a Service
- Windows 7 Testing Service Connectivity
- Determining Available Remote Management Protocols
- Why PortQry Is Great
- Task Manager
- Telnet Client
- Testing Service Connectivity
- Test TCP
- Windows Network Diagnostics
- The Process of Troubleshooting Network Problems
- How to Troubleshoot Network Connectivity Problems
- How to Troubleshoot Application Connectivity Problems
- Default Port Assignments for Common Services and Tasks
- How to Troubleshoot Name Resolution Problems
- How to Verify Connectivity to a DNS Server
- How to Use the Hosts File
- How to Troubleshoot Performance Problems and Intermittent Connectivity Issues
- How to Troubleshoot Joining or Logging on to a Domain
- How to Verify Requirements for Joining a Domain
- How to Troubleshoot Network Discovery
- How to Troubleshoot File and Printer Sharing
- How to Troubleshoot File and Printer Sharing from the Client
- How to Troubleshoot File and Printer Sharing from the Server
- How to Troubleshoot Wireless Networks
- Network Diagnostics
- How to Troubleshoot Firewall Problems