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Scott Arciszewski

Software, Privacy, Security, Innovation

Coping With a DNS Outage

August 1, 2014 11:50 PM • Innovation, Migrated, Tutorial

This was originally posted on a website I was developing over a year ago called Keenotes.


If you are in a sufficiently large corporate, government, financial, or educational institution, chances are your IT department runs their own DNS service. However, like with any network or device, downtime can strike anywhere.

If DNS downtime happens, you'll probably notice some connection problems: Websites you have not visited recently will not load, but the rest will pop right up like normal. This is because DNS results are cached by your operating system. You can usually diagnose this by running these commands:

Microsoft Windows XP/Vista/7/8 - use Command Prompt:
ping google.com
nslookup google.com
Mac OSX, FreeBSD, Linux - use the Terminal:
ping -c 4 google.com
whois google.com

(replace google.com with your institution's domain name, such as ucf.edu)

Great, we know the DNS server is down. Now what? Well, there are a couple of options available to you:

  • Add your voice to the cacophony of complaints that are essentially DDoSing the IT department who is desperately trying to fix the problem before they are overtaken by the deluge of angry employees, OR
  • Just use a differenet DNS provider and go about your business

The latter option is definitely more attractive than the first. So how do we do it? First we'll need some DNS servers we can use until the IT staff get the local server back online. Two popular options include Google DNS and OpenDNS.

Google DNS IP Addresses:  8.8.8.8 and 8.8.4.4

Open DNS IP Addresses:  208.67.222.222 and 208.67.220.220

For Windows users, open the Network and Sharing Center. This can be accomplished by going from the Start Menu, clicking on Control Panel, (optionally Network and Internet,) then Network and Sharing Center. Mac and Linux users should consult the guides for OpenDNS or Google DNS. Rewriting the instructions here would just be redundant especially since I do not have a Mac or every distribution of Linux at my disposal.

On the left side of this window, click "Change adapter settings."

Right click on your active internet connection (likely "Local Area Connection" or "Wireless Network Connection" and click Properties.

You should see a bunch of options, but the one you are looking for is Internet Protocol Version 4 (TCP/IPv4). You may also need to configure Internet Protocol Version 6 (TCP/IPv6). If you only see Internet Protocol (TCP/IP) then you are using version 4.

Keenot.es Image

Highlight the protocol (TCP/IPv4 for most people) then press the Properties button. Another window will pop up.

Keenot.es Image

Select "Use the following DNS server addresses:" then enter the IP addresses for your desired DNS server in the preferred and alternate DNS server fields. When you are finished, press OK. Press OK again to close the Adapter Properties.

Now, you want to verify that your DNS is working. Try running the ping and nslookup commands above. If they work, congratulations, you're using DNS while nobody else can. Be sure to revert the settings back to what they were originally when everyone else has internet access again so you can continue to access intranet resources.

If you're still having issues loading a webpage, try reloading. If that doesn't work, open command prompt and type in the following command: ipconfig /flushdns

Warning: If you type the previous command on a computer before setting up the alternative DNS provider, that computer will forget the IP address for every domain name that it normally remembers, rendering the internet virtually inaccessible. While this is a good way to ruin someone's day (set up Google DNS or OpenDNS on your computer, run the command, then show that person you hate only the last step and go, "I dunno what happened, it worked on my computer, see?" before running it again to add to their frustration), this will ultimately lead to more work for the IT staff and would generally be received as a poor decision amongst your coworkers, unless they all hate the person in question.

That's all there is to it. Enjoy your uninterrupted access to the internet.

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