I am trying to setup a distributed high availability proxy. Each proxy server should be located at different regions. DHCP Server can be used to inform the client machines to use proxy server which is available. Can you suggest a suitable method or some helpful links ? When I checked, solutions are available with heartbeat and haproxy but I am not sure how it will work if the servers are located in different regions. Thank you
You ask two distinct things:
To configure browsers to use a certain Proxy via DHCP, you need to set up a PAC server like this http://agix.com.au/blog/?p=912. PAC server is a simple HTTP server serving static files. Then add these two lines to your ISC-DHCPD configuration
option local-pac-server code 252 = text; option local-pac-server "http://www.example.com/wpad.pac";
To set up a high availability network you need to use a DNS round robin scheme: http://en.wikipedia.org/wiki/Round-robin_DNS
Should you need further help, I'd suggest cutting your post in two (client and server as noted above). Also you should consider moving them to the superuser.com StackExchange since that is a community dedicated to administrating many servers. People there will have more experience with providing High Availabilty to clients.