ARP is used only on and among local subnets -- to convert IP addresses to MAC addresses (the serial number of the NIC, if you will) and MAC addresses to IP addresses.
A local DNS server can replace or supplement various /etc/hosts files, or their equivalents on each OS. It can also act as a "local network resolver cache" for resolutions of Internet addresses made by requests from machines on the local network. A request from "Barbie" to resolve the IP address for yahoo.com can be obtained from the local server by "Ken".
But even the DNS server needs to have at least two records for every host provisioned -- one for each direction: IP address to name, name to IP address. This is usually a manual operation, but because DNS is designed to be a tree of servers, each server in most cases only needs a small, humanly managed configuration. And yes, the Internet's DNS, if you combine all the servers interconnected by it, is a very, very large tree.
|