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  • Help! DNS Issues after Wsus

    I just installed WSUS and now am having DNS issues... some sites work and some won't resolve...

    The only thing I can think of is that we are on a slower connection (which is why I wanted to use WSUS rather than each client connect)... WSUS is downloading the files from the internet (and I think it's killing the small 1.5 dsl connection we have).

    How do I throttle wsus or fix this issue! Please help me... our server is going whacko right now....

  • #2
    Re: Help! DNS Issues after Wsus

    Take some traffic samples of the DNS server when your clients are trying to resolve names and see what the hang up is. Check event logs too. You could use forwarders like OpenDNS to speed things up since using root hints causes a lot of ping-ponging between DNS servers to look up a single record.
    Wesley David
    LinkedIn | Careers 2.0
    -------------------------------
    Microsoft Certifications: MCSE 2003 | MCSA:Messaging 2003 | MCITP:EA, SA, EST | MCTS: a'plenty | MCDST
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    • #3
      Re: Help! DNS Issues after Wsus

      I stopped WSUS and things are working fine again so I am pretty sure that was the issue...

      Not sure how to take dns samples... can you explain?

      Also, if I used OpenDNS would I just set that up in the router or is there something on the server I would need to do?

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      • #4
        Re: Help! DNS Issues after Wsus

        Originally posted by chakotay2 View Post
        I stopped WSUS and things are working fine again so I am pretty sure that was the issue...
        Interesting. It could be just because it saturated your slow broadband connection as you stated. Or maybe something else.

        Originally posted by chakotay2 View Post
        Not sure how to take dns samples... can you explain?
        I meant to use Wireshark or Microsoft Network Monitor on that server and start a packet capture to watch the flow of traffic. You can filter by DNS queries to make the capture more manageable. You can also turn on debug logging on the DNS server. I don't know much about that yet so I can't give you too many details. I think it's similar in concept to a packet capture that is set to only capture DNS traffic.

        Originally posted by chakotay2 View Post
        Also, if I used OpenDNS would I just set that up in the router or is there something on the server I would need to do?
        On your DNS server, follow these instructions to put the IP address of OpenDNS's two DNS servers in as forwarders. Check out OpenDNS here. The two IPs for OpenDNS's servres are on the home page in the lower right corner. Make sure to read a little bit about OpenDNS and why it's so cool.
        Wesley David
        LinkedIn | Careers 2.0
        -------------------------------
        Microsoft Certifications: MCSE 2003 | MCSA:Messaging 2003 | MCITP:EA, SA, EST | MCTS: a'plenty | MCDST
        Vendor Neutral Certifications: CWNA
        Blog: www.TheNubbyAdmin.com || Twitter: @Nonapeptide || GTalk, Reader and Google+: [email protected] || Skype: Wesley.Nonapeptide
        Goofy kitten avatar photo from Troy Snow: flickr.com/photos/troysnow/

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        • #5
          Re: Help! DNS Issues after Wsus

          ok, will try those... if it turns out it's the bandwidth due to wsus/bits is there something else I could do (other than buying a bigger pipe?)

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          • #6
            Re: Help! DNS Issues after Wsus

            Just let WSUS download over the weekend? It won't drain your bandwidth forever. Also, adjust your WSUS synchronization schedule to only download updates from Microsoft on off hours.
            Wesley David
            LinkedIn | Careers 2.0
            -------------------------------
            Microsoft Certifications: MCSE 2003 | MCSA:Messaging 2003 | MCITP:EA, SA, EST | MCTS: a'plenty | MCDST
            Vendor Neutral Certifications: CWNA
            Blog: www.TheNubbyAdmin.com || Twitter: @Nonapeptide || GTalk, Reader and Google+: [email protected] || Skype: Wesley.Nonapeptide
            Goofy kitten avatar photo from Troy Snow: flickr.com/photos/troysnow/

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            • #7
              Re: Help! DNS Issues after Wsus

              Ok, will try that... Maybe I will just approve a couple at a time... since it was the first synch there were a TON to download.

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              • #8
                Re: Help! DNS Issues after Wsus

                Note that Wireshark and similar apps will work on machines in the same switch. Some switches will not redirect traffic to the port your Wireshark app is running on and thus you will not see any traffic. Put Wireshark on the same switch as your source & destinations.
                |
                +-- JDMils
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                +-- Regional Systems Engineer, DotNet programmer & Jack of all trades
                |

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                • #9
                  Re: Help! DNS Issues after Wsus

                  Originally posted by JDMils View Post
                  Note that Wireshark and similar apps will work on machines in the same switch. Some switches will not redirect traffic to the port your Wireshark app is running on and thus you will not see any traffic. Put Wireshark on the same switch as your source & destinations.
                  I'm not sure I follow you, can you explain that a little more for me?
                  Wesley David
                  LinkedIn | Careers 2.0
                  -------------------------------
                  Microsoft Certifications: MCSE 2003 | MCSA:Messaging 2003 | MCITP:EA, SA, EST | MCTS: a'plenty | MCDST
                  Vendor Neutral Certifications: CWNA
                  Blog: www.TheNubbyAdmin.com || Twitter: @Nonapeptide || GTalk, Reader and Google+: [email protected] || Skype: Wesley.Nonapeptide
                  Goofy kitten avatar photo from Troy Snow: flickr.com/photos/troysnow/

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                  • #10
                    Re: Help! DNS Issues after Wsus

                    I think he is talking about a span port (Switched Port Analyzer) or port mirroring.
                    Marcel
                    Technical Consultant
                    Netherlands
                    http://www.phetios.com
                    http://blog.nessus.nl

                    MCITP(EA, SA), MCSA/E 2003:Security, CCNA, SNAF, DCUCI, CCSA/E/E+ (R60), VCP4/5, NCDA, NCIE - SAN, NCIE - BR, EMCPE
                    "No matter how secure, there is always the human factor."

                    "Enjoy life today, tomorrow may never come."
                    "If you're going through hell, keep going. ~Winston Churchill"

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                    • #11
                      Re: Help! DNS Issues after Wsus

                      Sorry, I'm no expert on networks, but check this out:

                      http://www.wireshark.org/faq.html#q7.1
                      |
                      +-- JDMils
                      |
                      +-- Regional Systems Engineer, DotNet programmer & Jack of all trades
                      |

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