Dowling ResNet Troubleshooting Guide

Network Operations Center -- 8/2007

Here are some of the reasons why you might not be getting to the Internet.

Note: Windows Vista/7 has an entirely different set of problems with which we have only minimal experience at the moment. The instructions below apply to Windows XP with sp2. There is some crossover to Vista/7, but your mileage may vary.

Here are some possible solutions:

  1. Are you using wireless?
  2. You should try turning off your wireless NIC to see if it helps, also to avoid numerous problems that can plague both you and your neighbors. See resnet.html, the section named "What you must NOT do," and the first section of our routers page.

  3. Did you register properly at the "dormlord" web site? See resnet.html and res-connection.html .
    • Check that you have given us the right MAC (physical) address - see macaddress.html
    • Make sure you entered the physical address of your Local Area Connection OR your Wireless Network Connection. If you entered the wrong one when you originally registered your PC, register again with the right PHYSICAL address.
    • If you are running a router against our advice, make sure you gave us the ROUTER's WAN / Internet port Physical (MAC) address. See routers.html.
    • If your PC/device is failing to connect , then the "register your PC" situation is not the issue...keep reading.

  4. Is your network card "lighting up"? Once you've plugged your network cable into your PC/device and your network jack, lights indicate communication is occurring. No lights usually mean:
    1. Your cable is bad. Borrow another cable and try again. OR...
    2. Your network jack is bad. Temporarily connect to another jack in your room. If your PC's network card lights up, then your network jack is bad. Ask the Residence staff or your R.A. to fill out a work order form to get your network jack repaired.

  5. Are you getting a correct IP address? Check your IP address by following the directions at ipaddress.html. It should start with 149.72. If it does not start with 149.72, it's wrong. There are several possible causes:
    • If it starts with 169.254, your network wiring may be broken.
      • Try another network cable,
      • Try connecting to a different network wall jack.
      • Call or email the Help Desk to see if there is a widespread outage.
      • You may have a PC problem that we cannot help you with; consult with a PC repair expert.
    • If it starts with 192.168 one of your neighbors may be causing the problem with an unauthorized router.
      • Follow the instructions here to find out the MAC address and IP address of the offending router. Phone this information in to the Help Desk at 244-3445 during normal business hours, or email it to noc(at) from a working PC in the Library or a Computer Lab.
      • You may try a few times to fetch a correct IP address that starts with 149.72.
        • Click Start, Run, CMD
        • Type IPCONFIG  /RELEASE
        • Type IPCONFIG  /RENEW
        • Once you see an IP address that starts with 149.72, type EXIT - you're OK for now.
        • Alternately, rebooting your PC will also try to fetch a new IP address.
      • If you still cannot get a correct IP address, make sure you have given us the MAC (physical) address and IP address of the offender, wait a few hours, and try again. If you want to go out in the hall and shout, "Who's the idiot with the router?" that's OK, also.

  6. Has your PC's network software become corrupt? This can happen during virus or spyware cleanup, or as a result of spyware or a virus still residing on your PC. If you cannot browse to by name but you CAN browse to it at its IP address,, that's a strong indication that your PC has a spyware problem.
    • Make sure you have cleaned your PC using the tools on the Student Help CD, available at the Library or from your R.A..
    • If you're using a Norton/Symantec security suite, try uninstalling it. Norton's products, and sometimes McAfee's, sometimes get confused when you change networks - which is what you did when you moved your PC from home to Dowling. You may also need to run WinsockXPFix from the Student Help CD - look for it on the "Next Steps" page about 2/3 down. USE AT YOUR OWN RISK

  7. Have we blocked access from your PC for one of the reasons below? In all cases we first try to notify you at your Dowling email address, and alert you by redirecting your Internet browsing. If we do not receive a timely response, we will block ALL of your network access.

    • You may be running a router that's connected improperly and disrupting the network.
      Review the information at the routers.html page and fix the problem, then email us or phone the Help Desk.
    • You were identified by the RIAA or other recording industry entity as sharing copyrighted material.
      Follow the instructions on the "Copyright Notice" page and/or the email we sent to your Dowling student account.
    • Your PC may be infected with a virus and spewing dangerous or high-volume traffic on the Resnet.
      Borrow the Student Help CD from the Library or from an R.A. and follow the instructions it displays.

    You may be getting one of the "Grim Reaper" pages: Follow the instructions given on the respective pages, essentially: solve the problem, and tell us you have done so by emailing us your IP address from

Why all the fuss?

  • Unauthorized routers have caused disconnections for large numbers of students. We think it's fair that the person causing the disruption should lose internet access until s/he fixes the problem. If your router is causing a problem, we block your access.
  • RIAA/DMCA notices are legal documents that require us to take certain actions, like shutting down the source of the alleged copyrighted material. Until you respond according to the email and web page instructions we provide, we block your access .
  • Certain filesharing programs can cause ResNet to come to a grinding halt. When we spot such a program, we alert you and attempt to get you to cooperate in stopping the traffic. If that fails, we block your access.
  • Viruses and worms can cause significant slowdowns on ResNet, which adversely affects everyone's Internet access. If we spot worm traffic we try to alert you to the problem, and get you to use the tools and information we have provided to clean up the infection. If the traffic continues, we block your access.

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