How to Configure DNS Round Robin

Solution Unverified - Updated -

Environment

  • Red Hat Enterprise Linux
  • Bind

Issue

  • How to set up DNS Round Robin for load sharing or fault tolerance

Resolution

Round Robin DNS is a technique in which load balancing is performed by a DNS server instead of a strictly dedicated machine. A DNS record has more than one value IP address. When a request is made to the DNS server that serves this record, the answer it gives alternates for each request.

For instance, in order to distribute requests between three web servers, make following changes in DNS zone files.

; zone file fragment

www   IN  A   192.168.0.7
www   IN  A   192.168.0.8
www   IN  A   192.168.0.9

; or use this format, which gives exactly the same result

www   IN  A   192.168.0.7
      IN  A   192.168.0.8
      IN  A   192.168.0.9

Restart named service.

On RHEL 6:

#  service named restart

On RHEL 7:

# systemctl restart named

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