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DNS Issues

Posted on 2014-09-19
Last Modified: 2016-06-19
Over the last week I have had what would appear to be DNS issues appearing in our network.

Names have always resolved with no problems then it would seem out of know where they have started to not.

It appears to be random as to who is unable to connect to another PC on the network by name but the number of users appears to be growing.

They can connect by IP address no problem.

My DNS knowledge is pretty limited so don't want to go looking at settings and making thins worse.

Any ideas as to what could be causing this?

The only change I can think of is that a few months we upgraded our DCs from 2003 to 2012, could this be the issue and it is only coming to the surface now or would it of happened instantly?
Question by:Ben_Locke
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LVL 23

Expert Comment

ID: 40332176
Because we cannot really see your network and have no idea how things are set up it is somewhat wild guessing.

I think that you have not enabled your DHCP servers to automatically update the DNS server, this feature is called dynamic DNS and enables the DHCP server to let the DNS server know the ip address of a machine has changed. The fact that it could take a while for it to start occuring is that a default DHCP ip address is assigned for 7 days so only if a computer is not powered on for those 7 days will it receive a new ip address.

Are you able to ping to the servers by name? And it the name being resolved into a FQDN?? Also, are there A host records for these servers in DNS? If all of this is true, your DNS is at least working..

Author Comment

ID: 40332222
Thanks Rhandels,

It is very strange it seems to come and go, sometimes you can by name sometimes you can't.

The DNS has A host records for all the PCs. All the PCs have static IPs set also so they don't really change.

Ideas on what could cause it be inconsistent rather not working?
LVL 23

Expert Comment

ID: 40332235
So you are not using DHCP?? And when you check the A host record and the machines IP address they correspond?
Do you happen to have a new DNS server ip address and do the machines have the correct ip address for that DNS server?
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Author Comment

ID: 40332286
No, we only use a small DHCP zone for our wireless.

Yeah the host record and IP match.

The DC addresses stayed the same when we migrated so they still correspond with the PCs.

One thing that did change in the migration was the name of the DCs, could this have an impact? When I go to the properties of the zone in the forward lookup zone, in the 'Name servers' tab, the name of the new DCs are there but the names of the old DCs are still there too. Could this cause a conflict?
LVL 23

Accepted Solution

rhandels earned 500 total points
ID: 40332351
This could indeed cause confilct because the clients will try to contact those. If you are 100% sure the old DC's wont be coming back and are removed, then remove the records for those DC's (all references if any).

Author Comment

ID: 40332450
Okay thanks, I have removed them all references of the old DCs,

One more thing, when I am in the DNS manager on DC 2 in the tree on the left there is just iVR-DC2

But in the DNS Manager on DC 1 it has IVR-dc1 and IVR-dc1.domainname.local

Which both contain all the same info.

Is that right?
LVL 23

Expert Comment

ID: 40332485
Good question, not quite sure don;t have a DNS server at my dispoasal here. But if these are created manually i guess it will be allright. Do you still have issues then??

Author Comment

ID: 40332525
I will have to keep an eye on it, as I said it seems to be intermittent.

Will see how it goes for the next few days.

Thanks again
LVL 23

Expert Comment

ID: 40332550
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