Using westhost.com or 'domain' as the example, we'll review how DNS works.
At the top of the DNS chain is the Domain Registrar. Registrars provide registrations for custom Internet domain names like westhost.com or yourdomain.com. At the registrar level you can configure Domain Name Servers which will communicate the necessary resolution information for a domain name. Usually there will be at least two domain name server addresses for this purpose, which will be provided by your Web Host.
If you are with WestHost there are different domain name servers depending on your account, and you can always contact Tech Support with further questions about how to configure those for your domain.
DNS changes can take time to propagate throughout the Internet in order to work correctly. This can take 3-24 hours to complete. Allow up to 72 hours for complete worldwide propagation.
Once the DNS are set to a web host, then they will resolve to servers with that company, where the Domain Host information is stored. This points traffic through to the correct DNS Record for your domain. A DNS record includes all the parts which point your domain to the correct IP address of your server(s) which host the site content and e-mail for your domain.
A breakdown of record types is below.
The A Record [or Host Record] is the central record for DNS. This record links a domain or sub-domain to an IP address.
MX Records [Mail Exchanger] direct e-mail to server for a domain name, and are listed in order of priority with 0 being the highest. MX records point to a host/domain name for a mailserver.
CNAME Records [Canonical Name] are aliases for A Records. For each CNAME record you can choose an alias and an A record or host/domain name.