westhost is a subdivision of COM, and represents the Second-Level Domain.
cp is a subdomain or Third-Level Domain or CNAME.
The Internet simply wouldn't work without DNS. For most of us, remembering a long numerical address for every website we want to visit would be very difficult. Because of DNS, you don't ever have to remember the numerical addresses of websites.
Most Internet Service Providers (ISPs) have their own DNS servers that store a list of all the IP addresses and matching domains that have propagated to their network, plus a cache of IP addresses and matching domains for recently accessed servers outside the network. Each computer on each network needs to know the location of only one name server.
DNS is also used to find out where to deliver email for a particular domain.
Let’s continue by breaking down each section of a Domain Name.
TOP-LEVEL DOMAINS or TLDs are the last part of a domain name. These are the letters or short abbreviations after the last period. Some examples of common TLDs are: .com .net .org .biz .edu .co.uk
SECOND-LEVEL DOMAINS are the primary customizable part of a domain name as registered by a client. Some examples are: westhost or google, or wikipedia.
Combine the TLD and Second-level and you get westhost.com, google.com, and wikipedia.com.
THIRD-LEVEL DOMAINS are also known as subdomains and CNAMEs. In a full URL path, the subdomain is written before the domain name. Some common examples are: www, mail , or cpanel.