One of the more popular applications for DNS is for email. Although the web uses Domain Name Systems for linking names to IP addresses for web sites, email servers also require specialized records beyond what is required for basic domain host name to IP addresses. An email address is made up of two parts: a recipient and a host. In the email address mailmaster @ domain.tld, mail master is the recipient ie the user who will receive the message. The host, domain.tld refers to the mail server known as a mail exchanger.
A domain name usually consists of two or more labels, separated by dots. For example domainselectortool.com. The rightmost label conveys the top level domain. In this case domainselectortool.com has the top level domain .com. Each label to the left specifies a subdivision, or subdomain of the domain above it.
Subdomain expresses relative dependence not an absolute dependence. A host name refers to a domain name that has one or more associated IP addresses. The Domain Name System consists of a hierarchical set of DNS servers. Domain names or subdomains have one or more authoritative DNS servers that publish information about that domain and the name servers of any domains "beneath" it. The hierarchy of authoritative DNS servers matches the hierarchy of domains. At the top of the hierarchy stand the root nameservers: the servers to query when looking up a top-level domain name. Keyword searches for on the internet are performed on search engines. |
