How to Update the DNS Entry

For an illustration of how DNS maps a client to a cluster, see Figure A-6.

1. Start the nsupdate command.

   For more information, see the nsupdate(1M) man page.

2. Remove the current DNS mapping between the logical hostname of the application resource group and the cluster IP address for both clusters.

   > update delete lhost-nfsrg-prim A
   > update delete lhost-nfsrg-sec A
   > update delete ipaddress1rev.in-addr.arpa ttl PTR lhost-nfsrg-prim
   > update delete ipaddress2rev.in-addr.arpa ttl PTR lhost-nfsrg-sec

   ipaddress1rev

   The IP address of the primary cluster, in reverse order.

   ipaddress2rev

   The IP address of the secondary cluster, in reverse order.

   ttl

   The time to live, in seconds. A typical value is 3600.

3. Create a new DNS mapping between the logical hostname of the application resource group and the cluster IP address, for both clusters.

   Map the primary logical hostname to the IP address of the secondary cluster and map the secondary logical hostname to the IP address of the primary cluster.

   > update add lhost-nfsrg-prim ttl A ipaddress2fwd
   > update add lhost-nfsrg-sec ttl A ipaddress1fwd
   > update add ipaddress2rev.in-addr.arpa ttl PTR lhost-nfsrg-prim
   > update add ipaddress1rev.in-addr.arpa ttl PTR lhost-nfsrg-sec

   ipaddress2fwd

   The IP address of the secondary cluster, in forward order.

   ipaddress1fwd

   The IP address of the primary cluster, in forward order.