DNS records are stored in zone files and are used for translating domain names to IP addresses. They also contain other data, including the domain name's name server and mail server information. If there are domain name aliases, such as the commonly used "www" preceding the domain name, these will also be listed in the DNS record.
A typical DNS record may look something like this:
IN NS ns1.4servers.com. ; 123.456.789.01
IN NS ns2.4servers.com. ; 123.456.789.02
; Domain Mail Handlers
yourdomain.com. IN MX 0 mail
yourdomain.com. IN MX 10 mail
; hosts in order
yourdomain. IN A Your.IP.XXX
www IN A Your.IP.XXX
smtp IN CNAME www
pop IN CNAME www
ftp IN CNAME www
mail IN A Your.IP.XXX
Since DNS records are made up entirely of text, they are easy to modify when needed. However, one small typo could redirect a domain name to the wrong Web server or prevent it from showing up at all. This is why it is important to enter DNS information accurately and double-check your changes entry before saving the zone file.