What is ARP?

ARP CMD

 

ARP or Address Resolution Protocol, is the mapping of Internet Protocol (IP Address) address to the device hardware (MAC Address) address. This is probably better known to network admins for being used by network switches in the link layer ( ARP Tables).

Several operating systems provide tools to interrogate the data. In Microsoft Windows OS, the tool can be accessed via command line and the application is called “arp”.

 

More Info

At the command prompt i ran this command  – “arp -?”  and this is was the result:

 

Displays and modifies the IP-to-Physical address translation tables used by

address resolution protocol (ARP).

 

ARP -s inet_addr eth_addr [if_addr]

ARP -d inet_addr [if_addr]

ARP -a [inet_addr] [-N if_addr] [-v]

 

  -a            Displays current ARP entries by interrogating the current

                protocol data.  If inet_addr is specified, the IP and Physical

                addresses for only the specified computer are displayed.  If

                more than one network interface uses ARP, entries for each ARP

                table are displayed.

  -g            Same as -a.

  -v            Displays current ARP entries in verbose mode.  All invalid

                entries and entries on the loop-back interface will be shown.

  inet_addr     Specifies an internet address.

  -N if_addr    Displays the ARP entries for the network interface specified

                by if_addr.

  -d            Deletes the host specified by inet_addr. inet_addr may be

                wildcarded with * to delete all hosts.

  -s            Adds the host and associates the Internet address inet_addr

                with the Physical address eth_addr.  The Physical address is

                given as 6 hexadecimal bytes separated by hyphens. The entry

                is permanent.

  eth_addr      Specifies a physical address.

  if_addr       If present, this specifies the Internet address of the

                interface whose address translation table should be modified.

                If not present, the first applicable interface will be used.

Example:

  > arp -s 157.55.85.212   00-aa-00-62-c6-09  …. Adds a static entry.

  > arp -a

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