Windows 7 / Networking

How to Identify a Problem with the ARP Cache

To identify an incorrect entry in the ARP cache, first determine the MAC addresses and IPv4 addresses of hosts or gateways on the LAN with which the computer cannot communicate (as shown in the ipconfig /all example in this section). View the ARP cache on the computer that is experiencing the problem. Compare the output with the correct IPv4 address and MAC address combinations. If an entry is incorrect, clear the ARP cache to resolve the problem.

To determine the MAC address of a computer, open a command prompt and run the following command. Then find the Physical Address line in the output for your network adapter (which appears in bold in the code shown here).

ipconfig /all
Ethernet adapter Local Area Connection:
 Connection-specific DNS Suffix .  :
 Description . . . . . . . . . . . : NVIDIA nForce Networking Controller
 Physical Address. . . . . . . . . : 00-13-D3-3B-50-8F
 DHCP Enabled. . . . . . . . . . . : Yes

After you use IPConfig to determine the correct MAC address, you can view the ARP cache on the problematic computer to determine whether the cached address is incorrect. To view the ARP cache, open a command prompt and run the following command.

arp -a
Interface: --- 0xe

 Internet 	Address Physical 	Address Type 	00-e0-4d-dd-18-2a 	dynamic ff-ff-ff-ff-ff-ff 	static 	01-00-5e-00-00-02 	static 	01-00-5e-00-00-16 	static 	01-00-5e-00-00-fb 	static
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In this tutorial:

  1. Troubleshooting Network Issues
  2. Tools for Troubleshooting
  3. Table-1 Network Troubleshooting Tools
  4. Arp
  5. How to Identify a Problem with the ARP Cacher
  6. How to Clear the ARP Cache
  7. Event Viewer
  8. IPConfig
  9. Nblookup
  10. Nbtstat
  11. Net
  12. How to View Shared Folders on the Local Computer
  13. How to View Shared Folders on Another Computer
  14. Netstat
  15. Network Monitor
  16. Nslookup
  17. Verifying that the Default DNS Server Resolves Correctly
  18. Verifying that a Specific DNS Server Resolves Correctly
  19. Verifying Specific Types of Addresses
  20. Using TCP for DNS Lookups
  21. PathPing
  22. PathPing Output
  23. Routing Loops
  24. Performance Problems
  25. Possible Connectivity Issues
  26. No Connectivity Issues
  27. Performance Monitor
  28. Data Collector Sets
  29. Windows Resource Monitor
  30. Ping
  31. PortQry
  32. Identifying the TCP Port for a Service
  33. Windows 7 Testing Service Connectivity
  34. Determining Available Remote Management Protocols
  35. Why PortQry Is Great
  36. Route
  37. Task Manager
  38. TCPView
  39. Telnet Client
  40. Testing Service Connectivity
  41. Test TCP
  42. Windows Network Diagnostics
  43. The Process of Troubleshooting Network Problems
  44. How to Troubleshoot Network Connectivity Problems
  45. How to Troubleshoot Application Connectivity Problems
  46. Default Port Assignments for Common Services and Tasks
  47. How to Troubleshoot Name Resolution Problems
  48. How to Verify Connectivity to a DNS Server
  49. How to Use the Hosts File
  50. How to Troubleshoot Performance Problems and Intermittent Connectivity Issues
  51. How to Troubleshoot Joining or Logging on to a Domain
  52. How to Verify Requirements for Joining a Domain
  53. How to Troubleshoot Network Discovery
  54. How to Troubleshoot File and Printer Sharing
  55. How to Troubleshoot File and Printer Sharing from the Client
  56. How to Troubleshoot File and Printer Sharing from the Server
  57. How to Troubleshoot Wireless Networks
  58. Network Diagnostics
  59. How to Troubleshoot Firewall Problems