Windows 7 / Networking


Arp (Arp.exe) is a useful command-line tool for diagnosing problems in connecting to systems on a LAN where communications between computers do not travel through a router. Arp is also useful for diagnosing problems related to the client communicating with the default gateway. When a client contacts a server on the same subnet, it must address the frame with both the media access control (MAC) address and the IPv4 address. The MAC address is a 48-bit number that uniquely identifies a network adapter.

Arp is the name of a tool; it is also the acronym for the Address Resolution Protocol (ARP), which is used to find the MAC address corresponding to an IPv4 address. When a client communicates with a system on the same LAN, ARP broadcasts a message to all systems on the LAN asking for a response from the system that has the requested IPv4 address. That system responds to the broadcast by sending its MAC address, and ARP stores the MAC address in the ARP cache.

Note IPv4 addresses are used to identify computers on different networks. However, computers communicating across a LAN use MAC addresses to identify each other. ARP lets a computer look up a MAC address based on an IPv4 address so that two computers on the same LAN can communicate.

Problems with ARP occur only occasionally. For example, if a system changes its network adapter, clients might store the incorrect MAC address in the ARP cache. You can also manually place MAC addresses into the ARP cache, but if a manually added MAC address is incorrect, communications sent to that IPv4 address will not succeed.

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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