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Manual Chapter : Redirecting DNS Queries Using a CNAME Record

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BIG-IP GTM

  • 11.6.5, 11.6.4, 11.6.3, 11.6.2, 11.6.1
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Redirecting DNS Queries Using a CNAME Record

Overview: Redirecting DNS queries using a CNAME record

When you want to redirect DNS queries for a web site to a different web site, create a wide IP that represents the original web site, and add a pool configured with a CNAME to the wide IP to redirect the requests to the new destination.

The executives at siterequest.com recently purchased a competitor. Site Request's administrator wants to redirect DNS queries for competitor.com to a rebranded web site named competitor.siterequest.com.

About CNAME records

A CNAME record specifies that a domain name is an alias of another domain. When you create a pool with a canonical name, BIG-IP® Global Traffic Manager™(GTM™) responds to DNS name resolution requests for the CNAME with the real fully qualified domain name (FQDN).

Task summary

Perform these tasks to redirect a DNS request using a wide IP, which includes a pool that is configured with a CNAME.

Creating a pool using a CNAME

Create a pool to which the system can load balance DNS queries using a CNAME record, rather than pool members. For example, you can name the pool competitor_redirect and use a CNAME of competitor.siterequest.com.
  1. On the Main tab, click DNS > GSLB > Pools .
    The Pools list screen opens.
  2. Click Create.
  3. In the Name field, type a name for the pool.
    Names must begin with a letter, and can contain only letters, numbers, and the underscore (_) character.
    Important: The pool name is limited to 63 characters.
  4. From the Configuration list, select Advanced.
  5. In the CNAME field, type the canonical name of the zone to which you want GTM™ to send DNS queries.
    Tip: When you provide a canonical name, you do not add members to the pool, because the CNAME record always takes precedence over pool members. Additionally, a pool with a CNAME is not monitored for availability.
  6. Click Finished.

Creating a wide IP with a CNAME pool

Ensure that a pool configured with a CNAME exists in the BIG-IP® configuration.
Create a wide IP that includes a pool configured with a CNAME to redirect DNS queries for a web site, to a different web site.
  1. On the Main tab, click DNS > GSLB > Wide IPs .
    The Wide IP List screen opens.
  2. Click Create.
    The New Wide IP screen opens.
  3. In the Name field, type a name for the wide IP.
    Tip: You can use two different wildcard characters in the wide IP name: asterisk (*) to represent several characters and question mark (?) to represent a single character. This reduces the number of aliases you have to add to the configuration.
  4. From the Pool list, select the CNAME pool, and then click Add.
  5. Click Finished.

Viewing statistics for wide IP CNAME resolutions

Ensure that a wide IP that includes a pool configured with a CNAME exists in the BIG-IP® configuration.
You can view the number of DNS queries that GTM™ resolved using a CNAME record.
  1. On the Main tab, click Statistics > Module Statistics > DNS > GSLB .
    The Global Traffic statistics screen opens.
  2. From the Statistics Type list, select Wide IPs.
    Information displays about the cumulative number of DNS name resolution requests processed by the wide IP, and the number of requests load balanced using specific methods.

Implementation result

You now have an implementation in which BIG-IP® GTM™ resolves a DNS query for a wide IP to a CNAME. The LDNS must further resolve the CNAME to an IP address.

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