2

I am working on 2 scenarios:

Scenario 1: DNS A Record with 2 IPs [Default it works on Round Robin], but I am looking for option where if First IP not reachable then share 2nd IP.

Scenario 2: DNS A Record with 2 IPs [Default it works on Round Robin], If 1st IP is out of my LOCAL LAN & 2nd IP is of my LOCAL LAN, I should always get IP which is LOCAL to me. [Prioritize based on lowest time to reach].

DNS is always Central

Just looking for some configurations which can help me in this.

Thanks in advance

  • Search for "split-horizon DNS". – lcd047 May 18 '15 at 9:58
  • Where are you in the DNS configuration? – Ruban Savvy May 18 '15 at 10:00
  • Configured DNS slave master with ZONEs. – Ashish May 18 '15 at 11:13
  • split-horizon can solve only small part of 2nd Scenario. How can DNS Check Scenario 1 – Ashish May 18 '15 at 11:21
3

there is no such option built into DNS. And that is not an bind-specific thing.

A usual workaround is "Global Load Balancer Service", often referred to as gslb in cloud-contexts. This method does health checks on your services and replaces the a record with a "working one" in combination with a low TTL. But it has a little switchover time.

About the local LAN issue: The usual way is to make your firewall capable of "NAT reflection", i.e. do a proper NAT from internal to internal, then it might get ICMP redirects to save NAT traffic.

There is also something called "DNS Anycast" out, but that's way to complex for what to want to achieve.

HTH, even it does answer your question with "do it differently".

Best Regards, derjohn

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