October 7th, 2011, 10:40 AM
I'm a webadmin so some of this DNS stuff is a bit deep for me. I'm currently preparing a new cluster to go live and am running into some behavior I don't quite understand.
I have two servers behind a load balancer. The load balancer has a virtual IP and the servers have their own IP's. Sites/apps on the servers are accessed via port numbers.
DNS is still pointing at the old cluster. The new cluster is being tested by IP address directly and by resolving by my local hosts file.
When I bypass the load balancer and go to either node, I am fine. When I go to the IP address of the loadbalancer, I am asked to authenticate.
The wierd part is, when I added the name/IP combination to the local hosts file of my machine, some of the sites were accessible and others still prompted me for authentication. However, when I changed the spelling of the names to something other than what it registered in DNS (DMIntraTest vs. DMIntra) all the sites were reachable.
Can someone tell me why this is happening? It seems odd that the hosts file can resolve to a new name but halts on the actual name. Can it be conflicting with DNS somehow? And why would it not be reachable by IP?
Been wrestling with this for a little while now and have seemingly exhausted all my options.
Any input would be appreciated.
October 7th, 2011, 04:16 PM
Entries in your host files take precedence over DNS entries. If you have a domain mapped in your hosts file it will override any real DNS entries for that domain.
Your problem does not sound at all like a DNS problem. It sounds like it's either a problem with the load balancer, the web server or the application code.
What do you mean by a "virtual" IP?
It doesn't seem like that is the case to me. You've indicated that your new load balancer is experiencing an issue with prompting for a password. If you're getting a password prompt when you have the domain pointed to your load balancer via the hosts file then it certainly sounds like the domain is being pointed at the new load balancer, exactly as it's supposed to be.
Since bypassing the load balancer works fine, my guess is that the problem is with the configuration of the load balancer.