Domain Name System

Tags

networking

Refers to the collection of programs and databases that co-operate to resolve a host-name to an IP-address.

The DNS system is defined in a hierarchy of domain-name servers arranged as a inverted tree. At the top of the tree are the root servers for TLDs. Each name-server knows the IP addresses for the domains directly beneath them and so on and so forth.

DNS is carefully designed so that each machine can get away with the minimum amount of knowledge it needs to have about the shape of the tree, and local changes to subtrees can be made simply by changing one authoritative server's database of name-to-IP-address mappings.

The actual process of resolving an IP address has us querying the root name server and then recursively querying any subdomain name-servers until we find the domain we're interested in.