Manual Chapter : Redirecting DNS Queries Using a CNAME Pool

Applies To:

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BIG-IP DNS

  • 14.0.1, 14.0.0

BIG-IP LTM

  • 14.0.1, 14.0.0
Manual Chapter

Redirecting DNS Queries Using a CNAME Pool

Overview: Redirecting DNS queries using a CNAME pool

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 type to the wide IP with an A record type 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 CNAME pool with members specifying the canonical name, BIG-IP® DNS responds to DNS name resolution requests for A or CNAME name record type queries with these names if this pool is added to the said wide IP.

Redirecting DNS queries using a CNAME pool

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

Creating a CNAME pool

Create a CNAME pool to which the system can load balance DNS queries. For example, you can name the pool
competitor_redirect
and use a pool member name of
competitor.siterequest.com
.
  1. On the Main tab, click
    DNS
    GSLB
    Pools
    .
    The Pool List screen opens.
  2. Click
    Create
    .
    The New Pool screen opens.
  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.
    The pool name is limited to 63 characters.
  4. From the
    Type
    list, select the
    CNAME
    type.
  5. In the Members area, for the
    Member List
    setting, from the
    Wide IP
    list, select either a pool member (A or AAAA type) or a static target, and then click
    Add
    .
  6. Click
    Finished
    .

Creating a wide IP with a CNAME pool

Ensure that a pool configured with a CNAME type exists in the BIG-IP configuration.
Create a wide IP that includes a pool configured with a CNAME to redirect DNS queries from 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
    .
  3. In the
    Name
    field, type a name for the wide IP.
    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
    Type
    list, select a record type to serve from the required DNS query types.
    If you want the BIG-IPDNS to respond to both A and CNAME record type requests, you must configure two wide IPs. One wide IP of type A with a CNAME pool type, and a second wide IP of type CNAME with a CNAME pool type. At a minimum, an A record type wide IP should be configured with a CNAME pool.
  5. In the Pools area, for the
    Pool List
    setting, from the
    Pool
    list, select the name of the CNAME pool, and then click
    Add
    .
  6. 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 BIG-IP DNS (formerly 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® DNS resolves a DNS query for a wide IP to a CNAME.