06-03-2012, 03:26 PM
Address Conversion Functions and The Domain Name System
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Hostnames
IP Addresses are great for computers
IP address includes information used for routing.
IP addresses are tough for humans to remember.
IP addresses are impossible to guess.
ever guessed at the name of a WWW site?
Domain Name
The domain name for a host is the sequence of labels that lead from the host (leaf node in the naming tree) to the top of the worldwide naming tree.
A domain is a subtree of the worldwide naming tree.
DNS Organization
Distributed Database
The organization that owns a domain name is responsible for running a DNS server that can provide the mapping between hostnames within the domain to IP addresses.
So - some machine run by RPI is responsible for everything within the rpi.edu domain.
DNS Clients
A DNS client is called a resolver.
A call to gethostbyname()is handled by a resolver (typically part of the client).
Most Unix workstations have the file /etc/resolv.conf that contains the local domain and the addresses of DNS servers for that domain.
