Domain
- Tags
- networking
Refers to a collection of machines that share a common name suffix. Domains can live
inside other domains, for example www.tldp.org
lives in the .tldop.org
subdomain of
the .org
domain.
Domain Name
Is a human-readable identifier for a given host within a domain.
Format
A domain name is a case-insensitive series of labels all joined together by a
full-stop.
Each label of a domain-name can divide the domain into subdomain, with the right-most
domain being the most encompassing. So www.google.com
is a sub-domain of google.com
which is a sub-domain of the TLD .com
.
Sub-domains are often used to designate a particular host server. For example
ftp.example.com
can point to a file-transfer server below the example.com
domain.
Authoritative Name Server
Each domain has a dedicated name server that knows the IP addresses of the other machines in the domain. In many cases such a name server may have backup servers which take over when the main one gets taken down. Such servers may be referred to as secondary DNS.
Note: The authoritative name server doesn't need to list know the IP address of all
machines in that domain. It suffices to know the IP address of the name server for
each sub-domain that may be referenced. So the name-server for .org
may know the IP
address of the name-server for .tldp.org
but does not need to know the ip-address
of all the other machines in .tldp.org
.