This is a list of common terms that you'll encounter when managing a domain.

Since registrars, hosts, and record configurations vary, this is a basic guide to DNS.


DNS stands for Domain Name System. This system is in place to organize and identify domains. Essentially, DNS provides a name for a domain's one or more IP addresses. For instance, the domain name might translate to 198.102.434.8. This makes it much easier to remember URLs and email addresses.

DNS is also used to find out where to deliver email for a particular address. This is done with MX Records.


Domain Name

Domain names are easy-to-remember names (URLs and email addresses) that are associated with one or more IP addresses. Since a web page is defined by its URL, the page can move to a different IP address without affecting visitors.


  • is the domain name.
  • com is the top level domain.
  • singlespeed is a subdivision of com, and represents the second-level domain.
  • www is a subdomain (also known as third-level domain or CNAME).

The whole domain name can not exceed a total length of 255 characters, but some registries have shorter limits.


Domain Registrar

Domain registrars sell Internet domain names (ex. or ). Most of these companies offer a hosting service in addition to registration.

If your domain registrar is separate from your domain host, you'll need to add the host's name servers to your registrar's account. For example, if you purchase a domain name from (which offers domain registration) and host your domain with DynDNS (which offers domain hosting), you'll add the name servers of DynDNS ( and to your account with


Top Level Domain

Top-level domains are the last part of a domain name - the letters after the last period. Some examples are: biz com org edu us ca fr de travel local es pl


Second-level Domain

Second-level domains are directly below top-level domains. Some current examples are:

    Second-level DomainDomain Name


Third-level Domain

Third-level domains are also known as subdomains and CNAMEs. In a URL, the subdomain is written before the domain name. Here's some examples:



Domain Host

Domain hosts run DNS servers for your domain. This includes A records, MX records, and CNAME records. Most domain hosts offer domain name registration as well.


A Record

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.


NS Record

Name server records determine which servers will communicate DNS information for a domain. Two NS records must be defined for each domain. Generally, you will have a primary and a secondary name server record - NS records are updated with your domain registrar and will take 24-72 hours to take effect.

If your domain registrar is separate from your domain host, your host will provide two name servers that you can use to update your NS records with your registrar.

If you're not sure who is hosting your domain, you can perform an NS Lookup. Here's how:

  1. Visit
  2. Search for NS lookup.
  3. Select a search result.
  4. Type your domain name into the tool.
  5. Select NS records or Any records for your query.
  6. Click Look it up.

MX Record

Mail Exchange records direct email to servers for a domain, and are listed in order of priority. If mail can't be delivered using the first priority record, the second priority record is used, and so on.


CNAME Record

Canonical name records are aliases for A records. For each CNAME record, you can choose an alias and a host.

If you'd like to check the status of a CNAME record for web publishing, here's how:

  1. Visit
  2. Search for NS lookup.
  3. Select a search result from the list.
  4. Type your web publishing address in to the field.
  5. Select CNAME record if it's not the default search query.
  6. Click Submit, or Lookup.

IP Address

Internet Protocol addresses are unique numbers that allow devices to locate information on a network.


Custom URLs

Custom URLs, or short URLs, make using the Internet easier. A custom URL allows you and your users to access the login page for services at your domain with a simple, easy-to-remember address.


Calendar Examples

Domain Alias

Domain name aliases are additional domain names associated with your primary domain.

Some common uses:

  • Add a domain alias to cover other top-level domains. If your domain name is, you may want to alias and
  • Add a domain alias to help people who mistype your domain name. If your domain name is, you may want to alias,, and
  • Add a domain alias to receive mail addressed to two separate domains in one mailbox. If you receive mail at two domain names, such as and, you can alias to, and all mail sent to either address will be delivered to


WHOIS directory

The WHOIS directory is a public listing of domain names, and people or organizations associated with each domain name.

As a privacy measure, some domain name owners prefer to have their personal information hidden from the WHOIS directory. This is similar to the way someone may want his/her personal telephone number unlisted in a local telephone book.

The WHOIS directory is used to determine the owner of domain names and IP addresses. There are many free web-based directories available on the Internet. The information provided in the WHOIS directory includes a mailing address and a telephone number.