Duplicate PTR records

[marsdenprimary]

I've been having a few network issues recently with 'Limited or no Connectivity' occurring on a few of our PC's. I have a suspicion it could be something to do with duplicate ptr records:

I've attached a screenshot to see if you can help.
ScreenShot004.jpg

I'm not too fluent in server stuff like this so i'm just basing it on what i have been researching. I have set scavenging up to see if it removes these but i am assuming these duplicate IP's aren't right.

It's the other way round too with multiple IP's for different PC's.

[marsdenprimary]

The PC's only have one network card in them... and they're not set to receive different IP's- just an IP from DHCP. They're set to automatically receive an IP from our server but surely they should get rid of the old IP before getting a new one?

[djm968]

Scavenging should clear duplicates down. You can also try deleting both PTR records for one of the PC's, then on the PC open the command prompt and type ipconfig /registerdns

[marsdenprimary]

No just one DHCP server. The same server is also running DNS. We're only a primary school

[marsdenprimary]

OK, go to a dodgy machine and, from a cmd box, type ipconfig /all

See what that says. Have you got more than one IP address listed on the network card?
Check if your gateway is correct. See if you can ping it.
Type ROUTE PRINT from a cmd box. See if the gateway for destination 0.0.0.0 concurs with the one listed by ipconfig.

Compare the result with a machine that hasn't given you any trouble.

Checked all that as per your recommendation- all looks fine. Things match up. Only one IP listed.

I've also deleted the records and re-registered the DNS on the machine.

[marsdenprimary]

There don't seem to be any entries relating to DHCP (so i assume that's a good thing). The only errors to note really are 'Windows Update' entries- where the clients aren't updating.

[marsdenprimary]

I'm really, really grateful for all your help so far I can't see it being the network cards personally. It seems to have occurred all of a sudden after having network switches changed / new printer. Working out why they may be doing it is difficult because it could be all sorts.

From what I can tell the server could be a bit slow at assigning IP addresses and then the PC's are timing out and getting 'limited or no connectivity'. I wonder if this could be the issue?

[djm968]

The symptoms you describe seem to indicate that there is now something on the network creating mDNS broadcasts similar to Apples Bonjour service. As I suggested before the new Brother printer/driver or management software may be using multicasting to try and discover other devices on the network.

I would start by disconnecting everything from the switch and connecting just the server and one client computer. Then complete some basic IP and DNS tests.

When you are satisfied connectivity to this device is stable, you can start connecting other devices to the switch. I would start with the printer. You will also need to continue testing for a while after you connect each device as it may take some time for the switch react.

[marsdenprimary]

Hmmm... well as I was looking at the IP addresses that have been assigned by our server I came across a print server. Not our new printer but one i have never seen before. I have a feeling it's been there since I arrived but i've never noticed it.

I have no idea where it could be in our school but i'm going to hunt it down and ELIMINATE it! Hehe!! If I can find it... I'll keep you up to date.

Thanks for your advice djm- it's something worth doing but unfortunately not something i can really do while school is open. Holidays soon...

[djm968]

Thanks for your advice djm- it's something worth doing but unfortunately not something i can really do while school is open. Holidays soon...

No worries, its one of those things you tear your hair out trying to find..... hence I have very little hair left!

[marsdenprimary]

No worries, its one of those things you tear your hair out trying to find..... hence I have very little hair left!

I've actually just come across this on our new Brother printer whilst delving into its myriad of settings- did you mention something about mDNS??

Here's a screenshot to see if any of these enabled things could be causing a problem.
ScreenShot005.jpg

[djm968]

I've actually just come across this on our new Brother printer whilst delving into its myriad of settings- did you mention something about mDNS??

Here's a screenshot to see if any of these enabled things could be causing a problem.
ScreenShot005.jpg

Yes disable mDNS you don't need it as you have a domain controller on your network and it could be the issue.