I wish to understand the idea of anycast /dns based load balancing.
Let us assume situation is as follows Website is www.aaa.example There are 3 datacenters in Europe/Asia/america that I wish to loadbalance with haproxy loadbalancer on each datacenter and also httpd servers behind them hosting www.aaa.example (also route users to appropriate DC)
1.DNS based load balancer will have 3 entries in A record and round Robin algorithm. (How will europe users get to Europe DC)?
Anycast will be based on number of hops.
2.Those 3 loadbalancers will have diffrent public IP what will happen to user in europe when DC in Europe is down in DNS /anycast method?
3.Will user in any of those methods will see some error when accessing the site?
4.Finally is keepalived possibile on haproxy on public ips between diffrent DCS? (Is this even have a sense outside of local network)?