We have a system that has some issues I would like some help with. When we lose contact with our DNS server, which is on another network, EVERYTHING slows down. I ran Wire Shark on the interface of one of our clients while disconnected and found that it kept trying to query crl sites but it would never time out. We changed the DNS settings to include one address that was ping-able, but not running DNS Server services, and one fictious IP address that would not be reachable and ran Wire Shark again. This time we found queries to both addresses. The site which we could ping would reply instantly saying "Destination Unreachable". The fictious site would not reply at all (obviously) and the client would continue to query it. It would wait for the time out and query it again. Almost 100 times this would happen. The program which would normally take 2-3 minutes to load, was now taking 20-30 minutes to load. I went into the Host file on the client and added the crl websites to a new pingable address and loaded the program again. This time it was back to normal. So lets say my DNS server is 10.10.10.10 and my client is on 100.100.100.100. I set primary DNS to 10.10.10.10 and secondary DNS to 100.100.100.105. The secondary DNS is not a a DNS server, but a machine that is ping-able with the entries made in the HOSTS file. So if my primary goes down, it will look to the secondary and get a "Destination Unreachable" response and carry on as usual.
My question is two fold. First, is this ok to do? And second, what will happen when the primary comes back on-line?