There was a problem with an ISP last week who provide bandwidth to a customer colo rack. They are a major ISP who have done a reasonable job in the past. However, on Friday it took them 8+ hours to resolve a comms peering issue which was stopping about 5% of visitors getting to the WWW servers they were trying to reach. They temporarily resolved it by restarting their core switches. They don't yet know what caused the problem. All I know is that 5% of visitors didn't get to where they needed.
Anyway, I'm now been asked to have their WWW servers available from multiple geographical locations with the same hostname e.g. www.xyzzzzz.com
Someone has suggested multiple A records in DNS as a simple way to achieve this. The requirement is to keep the networks separate.
I need to find out more information on:
Are you similar round-robin-type DNS solutions to provide resilience for your web sites?
Are there standards for how a HTTP client (browser) decides which A record to use ? Will it make a random choice?
If the IP address of the 1st A record is not reachable do HTTP standards (and browsers) try the 2nd A-name record instead?
Thanks in advance for any feedback.