About CNAME Records (Alias Names)
CNAMEs or Canonical Names a.k.a. Alias Names are the user friendly names of the computers with complex hostnames. Alias names are created in order to make it easier for the users in the network to access a specific computer, without memorizing its complex name that is specified by the systems administrators in order to follow a consistent server naming convention.
Scenarios Where CNAMEs Are Required
In a typical production network, there might be cases when administrators want to make things easier for the users when it comes to accessing a computer with data that is to be used by everyone. Most common scenarios where administrators might want to use CNAMEs for the computers include:
- Computers with Complex Names – In almost all network environments, administrators follow a specific naming convention that has been defined earlier by the owner of the organization, or by the administrators themselves. In either case, when an important computer is renamed according to the defined naming convention, its name becomes a complex collection of alphanumeric and numeric characters, which also sometimes include hyphens. Since non-technical users that work in the organizations are not expected to memorize complex names for the servers, administrators make it easier for them to access such computers by creating corresponding CNAMEs for them.
- Computers with Lengthy FQDNs – In large enterprises, an entire Active Directory forest may contain multiple DNS namespaces, and each DNS namespace can have a root domain and a chain of few child domains up to third or fourth level. In such scenarios, sometimes it might be challenging for the users to locate a particular computer that belongs to the last level of domain chain. By specifying an alias name for such computer, administrators can ease its accessibility and can make its data available to all the users in the entire forest without having to memorize the entire FQDN of that computer.
Best Practices While Creating CNAMEs
Although administrators can use any name while creating an alias name for a computer, it is recommended that they should follow a globally accepted naming convention while doing so. For example, administrators should create an alias name for a printer server as ‘print.domainname.com’, and should avoid using illogical names such as ‘abc.printer.01’ or something like that.
Administrators must also make sure that the created alias name is fully functional and is redirecting users to the correct computer in the network. Mapping CNAME with wrong computer might result in unwanted data exposure to inappropriate users, hence compromising the security of highly classified information.
Create a CNAME Record for a Computer
To create a CNAME record in DNS database in Windows Server 2008 R2, administrators must follow the steps given as below:
- Log on to Windows server 2008 R2 DNS server computer with domain admin or enterprise admin account credentials.
- From the desktop screen, click Start.
- From the Start menu, go to Administrative Tools > DNS.
- On the opened DNS Manager snap–in, double-click to expand the DNS server name from the console tree in the left pane.
- From the expanded list, double-click Forward Lookup Zones.
- From the displayed zones list, click to select the DNS zone that contains the target host computer for which an alias name is to be created.
- Once selected, right-click the DNS zone.
- From the displayed context menu, click New Alias (CNAME).
- On New Resource Record box, type the desired user friendly name for the target host computer along with its Fully Qualified Domain Name (FQDN) in the Alias name (uses parent domain name if blank) and Fully qualified domain name (FQDN) for target host fields respectively. Alternatively, Browse button can also be clicked to browse for and locate the target host computer for which alias name is to be created.
- Once done, click OK to create the CNAME for the target computer.
- Close DNS Manager snap-in when done.