DNS problems?

Posted on 2004-11-05
Last Modified: 2010-04-14
Thanks in advance to anyone who can help with this...
I am the IT Admin for a small M2M communications company.  We have a mixed environment - Windows 2000 Server and Linux Red Hat Enterprise (3.0) for our servers, and Linux (Red Hat Fedora Core 1/2) and Windows 2000 professional for our workstations (of which there are about 20).  My questionis complex, so i will try to keep it simple.

We had an old (I mean really ancient) server (BEC, dual processor under 1GB, about 1 GB or RAM, 2 mirrored 160 GB drives) that was recently reformatted from Windows 2000 Server to Linux Red Hat Enterprise (3.0).  The people who reformatted decided to keep the same server name and server IP address.  Is this going to affect DNS or BIND in any way?  I had an instance before, when dealing with a rebuild of an Exchange server - in which the IP was changed from one that no longer existed to a new one, but the server name was kept the same.  This caused conflict where all the local workstations had the former IP Address listed in their hosts file, thereby causing massive delay in opening Exchange.  These workstations still have those hosts file, with the name of the server and the IP address in there.  Is this going to cause a problem?  I don't think it would since the name and the IP are the same, but since the OS is no longer Windows, I didn't know if DNS would freak out...
Question by:Jenn369
    LVL 70

    Accepted Solution


    It won't freak out or mind at all. But if you have DNS why the Hosts file entries?
    LVL 1

    Expert Comment

    I'm thinking the same thing...  If your network is using DNS servers, why is the hosts file being used?  Sure, it lessens the load on the network as workstations don't need to ask the DNS servers nearly as many questions, but because you have an individual copy of, basically, hard-coded values on 20 workstations, that makes 20 files that need to be updated to reflect changes.

    For simplicity, I highly recommend ditching the hosts file method and using just the DNS servers.

    Author Comment

    TY, Chris for such a quick response... I will award you the 250 pts(as long as I can figure out how to do that, as I am new to this end of this forum :)

    I agree with both of you re: the hosts file... however, my anti-Microsoft-products-bosses have decided I don't know what I'm talking about.  I am a girl, I look young, and I seem to encounter this problem any job I get - after all, I couldn't possibly know what I'm talking about. Most of my experience is with Windows, not Linux..    *shaking head*

    Anyway, some of the reasoning behind the hosts file was to speed things up and to reduce the network load, as part of the problem is the way the network is configured - we've got these great 3Com 3300XM 24 Port switches that can be configured to help things out considering we dont have much bandwidth to begin with (768kb)... but my bosses didn't even realize that the switches had the ability to be configured.  I had to show them the software disk it came with - they didn't believe me!!!!  And this is a communications company!!!!
    I dream of the day they install a T1 and allow me to make some major configuration changes....

    Perhaps the tech faery should visit the pcs at night and magically delete the hosts file :)  

    Thanks again for your help
    LVL 70

    Expert Comment

    by:Chris Dent

    Hey Jenn, I know that feeling well ;)

    All you need to do in DNS is add either A (Address) Records, or CNAME (Canonical Names or Aliases) for each device you intended to put in the Hosts File.

    So either:

    Server1 IN A
    Server1 IN CNAME

    DNS is intentially built with low network load in mind, in this situation the main reduction in load will come from client side caching. A Windows XP PC (for example) will ask DNS for the answer to a question about a name (hoping for an IP in reply). Once it has the answer it will add it to it's DNS Cache - stored in memory for 24 hours.

    The Local DNS Cache will flush if either the PC is rebooted or the command "ipconfig /flushdns" is run.

    Are you running BIND or Windows DNS? I can tell you how to make the relevant changes to either if you need them?
    LVL 70

    Expert Comment

    by:Chris Dent

    I can't spell intentionally for some reason... I blame fireworks.

    Author Comment

    I've got the server in question already in the DNS, my main concern was since it's now a Linux box, would Windows bark at it... Or would it just see it as the same?  I guess I'm a little confused as to how Windows "sees" the Linux pcs when it comes to DNS configuration....

    to make matters worse, since they didn't know what they were doing when they set things up, they are running both DNS and BIND...

    They want to host our own DNS in the future, so they've set  up a Linux server at a remote location to do that... it is also our mail server, running postfix and BIND... meanwhile, we still have an outside 3rd party hosting our DNS... and then we've got our Exchange server which is Windows locally... I am still struggling to piece all this together - started reading DNS and BIND, which is very good reading, but haven't made it to the chapters that can help yet...  I don't know all that much about Linux, or postfix, so I am at a loss as to what to fix where...  and when to update my resume, get some more certs and move on!!!!!
    LVL 70

    Expert Comment

    by:Chris Dent

    Ahh, that's a good book ;)

    You're using Active Directory in there? If so you need to have at least BIND 9 (or MS DNS 2000), Windows 200x domains require the ability to dynamically add entries to DNS - Service Records for Domain Controller, Kerberos KDC etc.

    Still, Windows is generally quite happy asking questions of BIND, DNS has a lot of standards to adhere to and compatibility between client side DNS Resolvers and the Servers themselves is one of them.

    Of course, some of the more interesting features of BIND (like Views) don't seem work too well from Windows machines.

    Author Comment

    Yes, AD spread throughout (like a virus *hee*)
    I know we're at least using BIND v.9, I remember checking to see what version it was several months ago...  everything seems to be ok at this point... guess I'm just trying to catch problems before they happen.. .which may just be a waste of time ...

    Thanks for clearing some of the DNS/BIND questions up...
    and thanks for helping me out..
    nice chatting with you  :)

    let me know if you are not awarded the 250 pts after I close this out- like I said, I'm new to this...
    thanks again!

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