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September 10, 2007 / Ben Chun

How the Internet Works

“How the Internet Works” is the name of my new unit for the freshman classes. I’m just trying to give a general overview. Today I introduced IP addresses, domain names, and DNS. I designed an activity using nslookup to inspect DNS records of common domains and look up domain names from IPs. Then, students will use the numeric IPs to access web sites and see that the mapping between domain and IP is not always as direct as it seems.

The only problem is that when the students log in, the command prompt is disabled in Windows. I guess this is supposed to enhance security or something. Anyway, I had to scramble this morning to find a DNS/reverse-DNS lookup utility thats free, doesn’t require administrative privileges to install (and preferably doesn’t need to be installed), and can do both forward and reverse DNS lookups. So far, I haven’t succeeded. The best I could do was dnsquery.

Any suggestions? This is turning out to be a lesson in how Windows gets locked down, instead of how the internet works. Or maybe this actually is how the internet always works. I wasn’t trying to be ironic, I swear!

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9 Comments

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  1. dsakima / Sep 10 2007 10:58 am

    Hey Ben!

    Here’s a web based DNS look up, is that kinda what you were looking for?

    http://www.zoneedit.com/lookup.html

    I’m glad your teaching this stuff, I’m afraid this is how kids see the Internet:
    1. Click blue E
    2. Search for ‘www.myspace.com’
    3. Click on the first search result for ‘www.myspace.com’

  2. Ben Chun / Sep 10 2007 11:45 am

    I was hoping to avoid using a web-based tool because I wanted them to see that their computer can (and has to) do DNS lookups for itself. But if I can’t find a decent little utility, and we’re locked out of the command line, perhaps a web interface is the best way to do it.

    I kinda like the simplicity of http://www.ipchecking.com

  3. Ben Chun / Sep 10 2007 9:06 pm

    And the winner is… PriaSoft NSLookup!

    http://www.priasoft.freeserve.co.uk/nslookup.html

  4. Ben Chun / Sep 11 2007 8:27 am

    I spoke too soon: PriaSoft NSLookup crashes under Windows 2000 (but not XP) when trying to do a lookup by address. Sigh.

  5. Sal M / Sep 11 2007 3:39 pm
  6. Sal M / Sep 11 2007 3:42 pm
  7. Ben Chun / Sep 12 2007 10:19 am

    Thanks for those links, Sal. I’m tempted to write my own GUI wrapper for nslookup. Who knew that teaching high school would actually lead back around to Windows programming? I thought I had escaped!

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