DNS question

Posted on 2012-09-04
Last Modified: 2012-09-10

I have the following question.
When I do nslookup in our domain I get below results:

Nslookup to mac-023 gives
Nslookup to gives lt-016
Nslookup to lt-016 gives and
- Nslookup to gives label-logistic
- Nslookup to gives lt-038

As you can see for example from mac-023 result = but in reveres it doesn't give mac-023.

Our external helpdesk say that this is a none issue, and that this doesn't give any problems.

Are they correct, or are there any known issues when this happens.
Question by:thecookiecompany
    LVL 20

    Expert Comment

    Did you perform each lookup from the same computer against the same DNS server?  If so, this may be indicative that the Forward Lookup Zone and Reverse Lookup Zone do not match - often caused by system latency or corruption in the database.  BUT don't be fooled by your own workstation caching these results.

    Try the same queries from another computer and see if you get the same exact results.  What happens to these results if you reboot and try again?

    Most company networks use DHCP (dynamic addressing) and machines may change addresses.  If DNS scavenging is not functioning, then stale entries can exist causing this symptom too.
    LVL 1

    Author Comment

    @Delphineous: Just tried it on a second computer and the results are the same as from my own workstation.

    Our company network is using DHCP for the most system, only servers have fixed IP adress.

    Are there any problems (like slow networking) known?

    The ressaon I ask this is: When I monitor our SQL server, I see computer names for example mac-023 which is not using this SQL server. So doing nslookup tells me that i can also be lt-016. That one can be using the SQL server.
    LVL 28

    Expert Comment

    by:Jan Springer
    The forward and inverse zones should match (excluding virtual hosts -- of which there will only be a forward entry).

    Have whoever takes care of your DNS correct this.
    LVL 7

    Accepted Solution

    To answer your original question, the reverse look up mismatch should not cause any slow down or other adverse effects in your network. Usually reverse look up is not even cared in general environments . Reverse look up is greatly used to verify the identity or the origination in Mail servers to reduce spam. For  example for a mail server it is required to match the smtp banner with the reverse look up name of the server. In your case it should not be a problem.

    Thank you

    Write Comment

    Please enter a first name

    Please enter a last name

    We will never share this with anyone.

    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.

    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…
    I've written instructions for one router type, but this principle may be useful for others of the same brand and even other brands of router. Problem: I had an issue especially with mobile devices that refused to use DNS information supplied via…
    how to add IIS SMTP to handle application/Scanner relays into office 365.
    Illustrator's Shape Builder tool will let you combine shapes visually and interactively. This video shows the Mac version, but the tool works the same way in Windows. To follow along with this video, you can draw your own shapes or download the file…

    759 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

    12 Experts available now in Live!

    Get 1:1 Help Now