Terms and definitions
DNS (Domain Name System)
DNS translates a domain name from an alphanumeric string (e.g.
YOURDOMAIN.COM) into a numerical IP address (e.g. 12.23.45.67).
Zone
The zone is the set of DNS records used to control how your domain
works, and to determine your domain and host IP addresses.
Record
Records are the elements that define the zone. A zone can include an
A, CNAME, NS, MX and TXT record. See definitions below.
Hostnames (A records)
Provide the IP address of the domain.
Aliases (CNAME records)
An alias can be used when you want to delegate a subdomain to
another nameserver.
Subdomain Delegations (NS records)
Domain nameservers hold information about how to reach your domain
name. NS records delegate authority for subdomains that are not on
the Managed DNS nameservers to alternate nameservers. For
example, if the zone information for OFFICE2.EXAMPLE.COM was hosted on
another nameserver (e.g. NS1.OTHERNAMESERVER.COM), the zone for
EXAMPLE.COM would need to include an NS record to delegate authority
to the other nameserver.
Mail Exchanges (MX records)
MX records are used to have mail delivered to your domain. Each mail
exchange has two pieces of information associated with it: the
hostname of the mail server, and a preference number. If there are
multiple mail exchanges, the mail server sending to your domain will
select one based on the preference level, starting with the lowest
number and working its way up.
TXT Records
TXT records are used to associate your comments to a hostname.
FQDN (Fully Qualified Domain Name)
A standard domain plus a hostname, ending with a period, e.g.
WWW.TUCOWS.COM. or DNS1.TUCOWS.COM.
Subdomain
| dns | adgrafics | | net |
| 3rd level | 2nd level | | 1st level |
A subdomain is a domain name that is part of a larger domain. For
example, RESELLERS.TUCOWS.COM is a subdomain of TUCOWS.COM.
Domain Name Levels
Domain names are divided into levels, starting from the end of the
domain and working left. The first level is also known as the Top Level
Domain (TLD) and is the .COM, .NET, .INFO, etc., element of the domain
name. For example, the domain RRC.TUCOWS.COM can be broken down
into the following levels: | 
