A DNS Zone is the roadmap of your domain, the DNS Zone contains the following:

• Nameservers assist in finding the server and correct the DNS zone for a domain in order to get the information on the other DNS zone records.
• NS records listed in the DNS zone must match the nameservers being used.
• A records point the domain to an IP address (e.g. mydomain.com -> IP address).
• CNAME records point subdomains to another domain name like www and mail. (e.g. www.domain.com -> domain.com).
• MX records control where emails are received. If the mail is to be hosted on another server, then the MX records are what need to be changed. (e.g. domain.com -> mail server).
• TXT records are custom records which contain machine-readable data. TXT records must be formatted according to whichever technology you are trying to use.