In some cases you may have multiple DNS A-records resolving to the same IP address assigned to a single host. Frequently this is the result of migrations and application consolidations from multiple distributed hosts to a single larger host. In many cases it is easier to leave the applications and clients configured to point to the older FQDN and simply update DNS to resolve to the new IP address of the active server.
You are configuring a CA XOsoft HA scenario and now need to update multiple DNS A-records in order to redirect all clients and applications to the replica server during a switchover.
Modify DNS to use CNAMES instead of DNS A-records
- Open the DNS management console and create a single DNS A-record for the Master FQDN which resolves to the IP address statically assigned to the Master server.
- Create a CNAME for each DNS Alias and point it to the Master server's (A) record*.
- Delete the DNS A-record Aliases from DNS.
- Create and configure a CA XOsoft scenario with DNS redirection to update the Master server (A) record. All of the aliases (CNAMES) will continue pointing to the Master (A) record and will all resolve to the Replica servers IP address following an XOsoft switchover.
*DNS A-Records resolve to an IP address, however CNAMES resolve to an A-record, which in turn resolves to the IP address.
** If you decide to add new DNS Alias, you will simply need to add them as CNAMES rather than A-Record.