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Same IP, multiple A entries within DNS, tied to multiple hostnames.

Posted on 2007-08-06
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Last Modified: 2013-11-25
Hi Guys...
I am in a bit of a fix. Two machines are replying with the same IP address but different hostnames. No, none of them is multihomed!!

I have both DNS and WINS enabled on my network.

Here's what exactly happens on my Windows 2003 AD network:
----------------------------------------------------------------------------
C:\Documents and Settings\f.s>ping ABC
Pinging abc.cnn.com [192.168.14.26] with 32 bytes of data:
Reply from 192.168.14.26: bytes=32 time<1ms TTL=127
Reply from 192.168.14.26: bytes=32 time<1ms TTL=127
Reply from 192.168.14.26: bytes=32 time<1ms TTL=127
Reply from 192.168.14.26: bytes=32 time<1ms TTL=127

----------------------------------------------------------------------------
Then I give the command:

C:\Documents and Settings\f.s>nbtstat -a 192.168.14.26
Local Area Connection 3:
Node IpAddress: [192.168.16.76] Scope Id: []

NetBIOS Remote Machine Name Table

Name Type Status
---------------------------------------------
XYZ <00> UNIQUE Registered
PCDOMAIN <00> GROUP Registered
XYZ <20> UNIQUE Registered
PCDOMAIN <1E> GROUP Registered

MAC Address = 00-04-75-E3-A4-1C
------------------------------------------------------------------------------

C:\Documents and Settings\f.s>ping xyz

Pinging xyz.cnn.com [192.168.14.26] with 32 bytes of data:

Reply from 192.168.14.26: bytes=32 time<1ms TTL=127
Reply from 192.168.14.26: bytes=32 time<1ms TTL=127
Reply from 192.168.14.26: bytes=32 time<1ms TTL=127
Reply from 192.168.14.26: bytes=32 time<1ms TTL=127

---------------------------------------------------------------------------------

I have confirmed that machine abc.cnn.com doesn't physically exist on my network, only machine xyz does.

Both the machines, ABC adn XYZ have an 'A' entry on my DNS server.

So, why and how does this entry of ABC come from? My IP addresses are dynamically allocated but then why is DNS/WINS keeping some old entries?

Any clues??
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Question by:fahim
6 Comments
 
LVL 31

Expert Comment

by:merowinger
ID: 19636738
make on both machines and on your dns server a
start-run->cmd
ipconfig /flushdns
ipconfig /registerdns
0
 
LVL 70

Expert Comment

by:KCTS
ID: 19637067
It would also be a good idea to enable aging and scavenging which will automatically clear out stale DNS entries

http://support.microsoft.com/kb/296116
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Author Comment

by:fahim
ID: 19644397
Thanks.
I was wondering, if WINS plays any role in this? Can I safely turn off my WINS? I have no pre-windows 2000 machines on my network.

Pls advise!!
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LVL 10

Expert Comment

by:Walter Padrón
ID: 19648720
Yes, it could be a record in WINS database.

Some services still rely on WINS for function or for some partial functionality but generally you can disable WINS if you have DNS + dynamic updates enabled. We disabled it long time ago.

Regards

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LVL 5

Accepted Solution

by:
richy92 earned 1000 total points
ID: 19736338
I dont think wins has anything to do with this - it just looks like you have an incorrect record in DNS. just use the DNS MMC to delete the record. If it comes back then either something is registering the record in DNS or perhaps the DNS database it out of sync. If after deleting the record it reappears have a look at the owner under security tab - may help to find out whos registering the record. Check the DNS database version is consistent across all DNS servers (it has a serial number in the soa record). Once you get it working its a good idea to set up scavenging as KCTS says or possibly if using DHCP get the DHCP server to register all records (although there are some security concerns).
Should be no problem switching off wins (stop the service on all WINS server and see what happens).
:)
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Expert Comment

by:Keith Alabaster
ID: 20010283
cmptrwhiz - I have now placed a member comment in your profile. Please take the time to read and digest its comments. You can find it here at the very bottom of the page.

http://www.experts-exchange.com/M_802166.html

Thank you

Keith_Alabaster
Networking Zones Advisor
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