Alright, not sure how to describe this the best...

We have a pretty big network at our college, several buildings and remote campuses.
At the main campus though, we are right now experiencing DNS problems, where clients failover to secondary DNS and third DNS, to 95% of the time directly on the bootup from one building only though. I wish there was a monitor program that somehow would show real time what DNS a workstation currently is using.. is there such a thing?!??
Anyway, how I know this is because people responsible to the DNS/DHCP server (one and same server) on the network has really set it up bad. DHCP is providing users this DNS configuration:
Preferred DNS: 10.x.x.55
Alternate DNS: 10.x.x.57
Third DNS: 216.x.x.x

If you use any internal DNS, everyone should know that you can't mix DNS servers like this, because if a workstation happens to fail over to the third EXTERNAL DNS, they now can't resolve any internal addresses at all!! Which is our problem. Customer can't get to the internal webservers at all, even right after reboot.

Here comes the tricky part though. Let say we go, oh well, lets live with the stupid DNS setup, at least it shouldn't fail over to the third DNS too often. If I boot up a workstation it right away sits on the third DNS, the external one, and can't resolve any internal DNS names. I do a ipconfig /renew and now it works... for a while, then of a sudden, like 5 minutes later, it has failed over to the third again, cause now I can't resolve internal DNS names again!
Also, ipconfig /renew usually goes in less than half a second, but every now and then it times out! (DHCP and DNS are the same server)
Even though I run a separate window with 'ping dnsserver -t', with less than 1ms respond time without one single hiccup during all this happening!!

It is true like the DNS people are saying, it didn't use to do it, they used to stay on the first internal DNS server and hardly ever fail over to the third. But now it keeps doing it at once!
What could cause this kinda messup?!

Should add that there is one hop with a 100 half duplex router between the two buildings, but it's been there for ages...not something new... but it still doesn't sound good to me to have a half duplex thing, not sure this really is the cause to our current problems.

Any good ideas to what could cause the DNS to fail over so quickly?!
Once connected to the external DNS though, it seems to stay just fine on that one.. !

Any help, greatly appreciated!

Thanks!