Problems With Static Configuration

There are a number of clear problems with static configuration of network attributes:

• System administrators may have to oversee hundreds of machines on a network. Manual maintenance of distinct files becomes intractable.
• A single (political) network domain may service many more (dialup or mobile) computers than it has registered IP addresses. Of course, this scenario hopes that not all computers wish to be connected at once.
• Mobile computers may wish to frequently connect to different (unrelated) networks, and
• Some previously trusted computers may become untrusted, and system administrators may have lost access to modify their configuration files.

A partial solution

The most 'stable' attribute in most networking configurations is the network interface card's MAC address, such as a card's 48-bit Ethernet address. (many new Ethernet cards can change their MAC addresses programmatically - a mixed blessing!)

As with the ARP protocol described earlier, a newly booted client computer can broadcast its Ethernet address via the Reverse Address-Resolution Protocol (RARP).

The client broadcasts its RARP request, and any host acting as a RARP server may reply with the client's allocated IP address.