Wireless Networks Thread, Machines returning same IP address in Technical; Not sure how to explain this one, but we have about 250 machines on the network, but there are about ...
30th April 2008, 04:13 PM #1
Machines returning same IP address
Not sure how to explain this one, but we have about 250 machines on the network, but there are about 4 or 5 machines that when i try to ping them by the computer name they return the same IP address.
Hopefully this is something easy to resolve.
Have attached screen shot of two computers i know about.
Last edited by tomscaper; 30th April 2008 at 04:31 PM.
IDG Tech News
30th April 2008, 04:15 PM #2
Hmmm are these machines reporting IP conflicts at all? what happens if you do nslookup for both machines?
30th April 2008, 04:19 PM #3
I'd check the DNS entries on the server. I take it they have different IPs when you do ipconfig on the machines locally.
Thanks to SYSMAN_MK from:
30th April 2008, 04:26 PM #4
Enable scavanging on your rDNS zone.
30th April 2008, 04:29 PM #5
Yes if i were to do ipconfig on the machine themselves it would bring up different IPs
Originally Posted by SYSMAN_MK
I am not sure how i would check the DNS entries on the server, any chance you could explain where to look.
The computers themselves all work and connect, but for some reason i cant ping them by name.
30th April 2008, 04:32 PM #6
This is what nslookup reports
Originally Posted by Jona
30th April 2008, 04:38 PM #7
In the above examples, what are those two machines real IP addresses?
30th April 2008, 04:42 PM #8
staff-01 has 10.64.17.176
res-13 has 10.64.17.68
Originally Posted by Geoff
30th April 2008, 05:02 PM #9
- Rep Power
I would firstly flush the local dns cache (ipconfig /flushdns)
Then repeat what youve done. If it the same then goto the DNS management console on your server or wks (administrative tools->DNS) Look at your forward lookup zones, in the domain name you should see a list of A records. Look for the entry and see if they have repeats, you can delete them here. Then do an ipconfig /registerdns and they should reappear in the dns properly. If someone has added them manually there could also be a C Name record for example, just check the names.
If this has happened then for it to work proper in the future the DNS scavenge needs to be switched on and setup with the right settings (as well as dhcp). Actually that reminds me about mine
Thanks to blacksheep from:
30th April 2008, 05:05 PM #10
yep. IPCONFIG /FLUSHDNS.
I end up doing it here sometimes..Netsupport does something similar on rare occasions..heh.
30th April 2008, 05:49 PM #11
We sometimes get duplicate entries in our DNS I guess because the machine aren't sometimes renamed or removed from the domain properly just delete the bad entires in DNS
@ Geoff how would you enable scavanging on your rDNS zone and should this be something thats done on a LAN?
30th April 2008, 08:48 PM #12
right click on the zone, and there's an option to set scavenging time or something like that. I believe the default is 14 days but You can then set the aging time in days to whatever you wish. There's also an option to scavenge resource records now, although can't remember if that's under rDNS options or somewhere else.
Originally Posted by FatBoy
We set scavenging to seven days and tried the scavenge now option...neither worked, so i think i'll have to just delete the duplicate records manually.
30th April 2008, 10:46 PM #13
Your scavenging period should be set to the duration of your DHCP leases.
It's a common mistake to change DHCP lease durations without changing the DNS scavenging periods.
This results in discrepancies in your DNS/DHCP databases with machines appearing to have the same or duplicate IP addresses in the DNS zone.
Whilst this does not normally affect the client PC's themselves if they share files or printers, others will not be able to find them and Group Policies will regularly fail to apply on machines with multiple reverse DNS entries.
Others have already correctly advised you how to set this.
DNS DNS DNS, this is the core of Windows AD get this right and the rest is like falling off a log!
Get it wrong and your AD will eventually die, along with your reputation.
2 Thanks to m25man:
tomscaper (1st May 2008), torledo (30th April 2008)
1st May 2008, 09:57 AM #14
Ours is set to 8 days but I think it's got a lot to d with how many clients you have and what sort of DHCP range size you have set.
Also FYI I was looking around some of are settings and if you right click on your Scope in DHCP and go to properties, then the DNS tab and under here you have "Enable DNS dynamic updates according to the setting below". Ours was set to only update if the clients requests it so I have now changed it to "Always dynamically update DNS A nad PTR records"
1st May 2008, 11:00 AM #15
Have some rep! just checked my settings, way off - explains the odd discrepancy I've seen bit like the OP. All changed now
Originally Posted by m25man
By KeithFermor in forum Bad Experiences
Last Post: 30th November 2007, 03:52 PM
Last Post: 4th October 2007, 07:55 PM
By adamyoung in forum Thin Client and Virtual Machines
Last Post: 2nd October 2006, 10:35 AM
By witch in forum Hardware
Last Post: 14th June 2006, 12:25 PM
Users Browsing this Thread
There are currently 1 users browsing this thread. (0 members and 1 guests)