Windows NT TCP/IP Network Administration

Troubleshooting Network Access

The “no answer” and “cannot connect” errors indicate a problem in the lower layers of the network protocols. If the preliminary tests point to this type of problem, concentrate your testing on routing and on the network interface. Use the ipconfig, netstat, and arp commands to test the Network Access Layer.

Troubleshooting with the ipconfig Command

ipconfig checks the network interface configuration. Use this command to verify the user’s configuration if the user’s system has been recently configured, or if the user’s system cannot reach the remote host while other systems on the same network can.

When ipconfig is entered with the /all argument, it displays the current configuration values assigned to the interface. For example:

C:\ipconfig /all
Windows NT IP Configuration
        Host Name . . . . . . . . . : pooh
        DNS Servers . . . . . . . . : thoth
        Node Type . . . . . . . . . : Broadcast
        NetBIOS Scope ID. . . . . . :
        IP Routing Enabled. . . . . : No
        WINS Proxy Enabled. . . . . : No
        NetBIOS Resolution Uses DNS : No
Ethernet adapter SMCISA1:
        Description . . . . . . . . : SMC Adapter.
        Physical Address. . . . . . : 00-00-C0-9A-72-CA
        DHCP Enabled. . . . . . . . : No
        IP Address. . . . . . . . . : 172.16.12.2
        Subnet Mask . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . : thoth

The ipconfig command displays two types of information. The first type is information about the TCP/IP configuration. The second type is about the network interface and its characteristics. ...