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You’ll see something similar to the following:


Interface: 204.153.163.3 on Interface 2 Internet Address    Physical Address    Type


204.153.163.2    00-a0-c9-d4-bc-dc    dynamic


204.153.163.4    00-a0-c0-aa-b1-45    dynamic


The -g switch will accomplish the same result.


From this output, you can tell which MAC address is assigned to which IP address. Then, by examining your network documentation (you do have it, don’t you?), you can tell which workstation has the IP address and if it is indeed supposed to have it.


If the machine has more than one network card (as may happen in Windows NT machines), each interface will be listed separately.


In addition to displaying the ARP table, you can use the ARP utility to manipulate it. To add static entries to the ARP table, use the ARP command with the -s switch. These entries stay in the ARP table until the machine is rebooted. A static entry hard-wires a specific IP address to a specific MAC address so that when a packet needs to be sent to that IP address, it is sent automatically to that MAC address. Here’s the syntax:


ARP -s [IP Address] [MAC Address]


Simply replace the [IP Address] and [MAC Address] sections with the appropriate entries, like so:


ARP -s 204.153.163.5 00-a0-c0-ab-c3-11 You can now take a look at your new ARP table by using the ARP -a command. You should see something like this:


Interface: 204.153.163.3 on Interface 2


Internet Address    Physical Address    Type


204.153.163.2    00-a0-c9-d4-bc-dc    dynamic


204.153.163.4    00-a0-c0-aa-b1-45    dynamic


204.153.163.5    00-a0-c0-ab-c3-11    static


Finally, if you want to delete entries from the ARP table, you can either

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