A records (also known as host records) are the central records of DNS. These records link a domain, or subdomain, to an IP address. A records and IP addresses do not necessarily match on a one-to-one basis. Many A records correspond to a single IP address, where one machine can serve many web sites. Alternatively, a single A record may correspond to many IP addresses. This can facilitate fault tolerance and load distribution, and allows a site to move its physical location.

In Short

An A-record is an entry in your DNS zone file that maps each domain name (e.g. yourdomain.com) to an IP address. In other words, the A-record specifies the IP address to which the user would be sent for each domain or subdomain. “A” for “Address.”