What is a CNAME?
CNAME-Records (Canonical name for an alias)
CNAME-records are domain name aliases.
Often computers on the Internet have multiple functions such as web-server, ftp-server, chat-server etc.
To mask this, CNAME-records can be used to give a single computer multiple names (aliases).
For example computer xyz.com may be both a web-server and an ftp-server, so two CNAME-records are defined:
www.xyz.com = xyz.com and ftp.xyz.com = xyz.com.
Sometimes a single computer hosts many different domain names (take ISPs), and so CNAME-records may be defined such as abc.com = xyz.com.
The most popular use the CNAME-record type is to provide access to a web-server using both the standard www.domain.com and domain.com (without the www).
This is usually done by creating an A-record for the short name (without www), and a CNAME-record for the www name pointing to the short name.
CNAME-records can also be used when a computer or service needs to be renamed, to temporarily allow access through both the old and new name.
A CNAME-record should always point to an A-record to avoid circular references.
HOST NAME------RECORD TYPE-------Pref-----ADDRESS
Now mydomainname.com should point to an A Record
HOST NAME----RECORD TYPE----Pref----ADDRESS
You can also always use @ instead of the domain name in the \"host name\" field. The @ means the same thing as mydomainname.com
How does it work?
A CNAME (Alias) can be either a host name under this domain name (for example, mail or ftp). Note: When using a domain name, it should end with a period .. Example: www.xxxxx.com.
HOST NAME------RECORD TYPE----Pref-----ADDRESS
Now when someone types in secure.mydomainname.com they will be able to access such a page if it exists.
How long will it be before I can see my changes?
Allow 12 to 24 hours for external networks to update It is important to remember that information about your domain's web features may be retained by other networks across the Internet for a period longer then 12 to 24 hours.