Solved

2 IP addresses, choose what one to be returned in dns queries.

Posted on 2008-10-07
9
267 Views
Last Modified: 2010-04-07
Afternoon,

Our exchange server has two IP addresses.
One for lan, the other for WAN/PPP Interface.

When pinging the server name the WAN/PPP ip is returned, and thus the server is unaccessible.
If I flush the DNS and re-register it on the client experiencing this it will revert back to the LAN address..

But after a while it goes back to the WAN/PPP interface again.

How can I resolve this? What is the best solution, and why is this happening?
0
Comment
Question by:Alan-Yeo
9 Comments
 
LVL 40

Expert Comment

by:omarfarid
ID: 22660938
I am not sure if windows dns has a mechanism for preferred ip based on source ip address. On the other hand BIND can do that
0
 
LVL 70

Expert Comment

by:Chris Dent
ID: 22660945

Hi,

This happens because DNS uses Round Robin to respond to requests where multiple addresses exist for a single resource.

Do you really need two addresses? I recommend you set the WAN/PPP interface not to register entries in DNS to avoid conflicts.

Chris
0
 
LVL 70

Expert Comment

by:Chris Dent
ID: 22660965

> I am not sure if windows dns has a mechanism for preferred ip based on source ip address

It does, NetMask Ordering. It's pretty basic though, it will try and order round robin responses so an answer on the local subnet is returned first.

Reliance on it should be avoided though really. It would be better (from my point of view) to investigate why the WAN/PPP address is registering.

Chris
0
 
LVL 59

Expert Comment

by:Darius Ghassem
ID: 22661338
As Chris states go into your Network Connections righ-click the WAN NIC then go to properties highlight the Internet Protocol then click properties. Once in the properties click Advance then go to the DNS tab uncheck register with DNS.
0
IT, Stop Being Called Into Every Meeting

Highfive is so simple that setting up every meeting room takes just minutes and every employee will be able to start or join a call from any room with ease. Never be called into a meeting just to get it started again. This is how video conferencing should work!

 
LVL 40

Expert Comment

by:omarfarid
ID: 22661458
Hi Chris-Dent,

I am not aware of this "NetMask Ordering" feature in windows dns - thank you for bringing it, but BIND feature to response with a specific IP to a specific source IP is much better in this case.
 
0
 
LVL 70

Expert Comment

by:Chris Dent
ID: 22661532

> but BIND feature to response with a specific IP to a specific source IP is much better in this case.

You'll not find me arguing with that, Views are a feature I dearly wish could be implemented in MS DNS :)

It's just BIND tends to be a bit over the top for an AD Domain which is implied because of the Exchange part :)

Chris
0
 
LVL 26

Expert Comment

by:jar3817
ID: 22662490
Just add a route to the wan/ppp network via exchange's lan IP.
0
 

Author Comment

by:Alan-Yeo
ID: 22666920
The WAN/PPP connection is not in Network Connections.

I don't know where it comes from, but it shows up in ipconfig/all

NOTE: This particular server is a domain controller. (Not sure if that makes any difference) and it hosts the DNS Server.
0
 
LVL 70

Accepted Solution

by:
Chris Dent earned 500 total points
ID: 22667177

Well the second option is to change the Interfaces the server listens on, that would prevent even the server itself from registering the incorrect entry.

These are the instructions:

1. Open the DNS Console
2. Open the Properties for the DNS Server
3. Select Interfaces
4. Change the option to "Only the following addresses:"
5. Enter the IP address of the internal interface only

Then simply delete the erroneous entry from the forward lookup zone and check it doesn't reappear.

Chris
0

Featured Post

What Security Threats Are You Missing?

Enhance your security with threat intelligence from the web. Get trending threat insights on hackers, exploits, and suspicious IP addresses delivered to your inbox with our free Cyber Daily.

Join & Write a Comment

Most DNS problems are VERY easily troubleshot and identifiable if you can follow the steps a DNS query takes. I would like to share the step-by-step a DNS query takes from the origin to the destination. _____________________________________________…
One of the most often confused topics in the area DNS is the idea of GLUE records. Specifically, what they are, when they are needed, when they are provided, and how they are created. First, WHAT IS GLUE? To understand GLUE, you must first under…
Access reports are powerful and flexible. Learn how to create a query and then a grouped report using the wizard. Modify the report design after the wizard is done to make it look better. There will be another video to explain how to put the final p…
Here's a very brief overview of the methods PRTG Network Monitor (https://www.paessler.com/prtg) offers for monitoring bandwidth, to help you decide which methods you´d like to investigate in more detail.  The methods are covered in more detail in o…

706 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question

Need Help in Real-Time?

Connect with top rated Experts

14 Experts available now in Live!

Get 1:1 Help Now