Forum Discussion
NimbostratusAutomatic GTM failover
Hi All,
We are planning to deploy 2 GTM in delegate mode i.e. subzone for GTM managed wideip will be created on primary DNS server. The 2 GTM are in 2 different data center and requirement is all user traffic should be forwarded to Data Center 1 on GTM1, once the GTM1 is down then user DNS query should be forwarded to GTM2 which is on Data Center 2. Please suggest if this is possible as per my understanding the failover can be achieved manually i.e. by adding one GTM listener IP to delegated zone on primary dns and once the gtm1 is down we need to manually replace.
Simon_BlakelyEmployee
Your GTMs are referenced as the name servers for the delegated sub-domain. You either return both GTM ip addresses (in which case the client resolver will choose a nameserver from the supplied NS records), or only configure 1 NS record, and manually update this to direct traffic to the other nameserver.
Remember, the GTM that is queried for a wide IP does not influence the response address unless it is configured to do something different - in general, both GTM1 and GTM2 will return the same responses to DNS queries, so if GTM pool members (i.e. virtual servers in either DC1 or DC2) from DC1 are preferentially selected, both GTM1 and GTM2 will do so.
You have to strike a balance between reliability (having multiple NS server records for the sub-domain) and control over the destination of the traffic DC1/DC2. A manual failover operation to switch between DCs raises the risk of an interruption of service in an emergency, and you will need a short TTL on the SOA records, otherwise the failover change will take some time to propagate.
JGCumulonimbus
It would be helpful if it is clear what business benefits this particular idea, in comparison with any other, tries to achieve.