DNS Backup Plan
This morning I had an interesting problem. I was visiting Nozbe when I received an error from my DNS provider indicating the site had been blocked for phishing. I have a relationship with Nozbe so I figured this was a glitch with my DNS provider who offers an additional security layer. But I also knew that it would probably take time before the fix was made. In times like these, it's good to have a DNS backup plan.
If you're not familiar with DNS, it's the system that maps web addresses to IP addresses. For most people, it's much easier to remember web addresses then numbers. However, it's also helpful to see if you can reach the problem site using its IP address. You can find a domain's IP address using the Server Stats tab on Domaintools.com
Nozbe is a site where I have project details and tasks stored so I needed access. I didn't want to wait for my DNS provider to finish their phishing research. I figured the fastest alternative was to use another DNS provider. Once I had another provider, I just had to clear my DNS cache and browser to be back in business.
Using these steps, you can easily work around these problems. For many people, their DNS is provided by their Internet service provider (ISP), but there are also public DNS providers that can provide an alternative. In my case, I chose to use Google's public DNS.
How to find alternate DNS settings
There are a number of free public DNS services. The two I prefer are OpenDNS and Google. Because, I was having the problem with OpenDNS, I choose to swap in Google for one of the entries.
1. Go to http://code.google.com/speed/public-dns/
2. Write down the DNS settings on this page. You don't need to copy both number sets, just choose one set such as 8.8.8.8. You can still maintain your Secondary DNS setting. This way you only have one set to change back when the problem is resolved.
Entering your new DNS setting
Depending on your configuration, you either change your settings in your network router or on your PC. For many people, this setting is handled by your router. The instructions for each router are different, so it's best to consult your manufacturer or ISP. In some cases, the router login information is printed on the router.
Note: Before entering the new DNS info, I would write down the DNS setting you're replacing or take a screen capture.
Below is a screen print of the settings panel for my router. You can see where I substituted in the Google DNS for the Primary DNS. I've kept the Secondary DNS the same.
If you don't use a router, the settings are handled by your Windows configuration. In this scenario, you need to go to Control Panel and change your TCP/IP settings. Microsoft has a series of how to knowledgebase articles based on your operating system.
Change TCP/IP Settings - Windows 7
Change TCP/IP Settings - Vista
Flushing the DNS Cache
After you've changed the DNS, you need to clear your DNS cache. Otherwise, you'll get the same error until the domain entry expires.
- Go to your Start menu,
- In the Search box, type CMD
- Under Programs, select cmd.exe. You may have to run this as administrator.
- At the DOS command line prompt, type ipconfig /flushdns (Note: there is a space between the two.)
- Press Enter
When you press Enter, the system will respond with Successfully flushed the DNS resolver cache. If you don't get that, you probably mistyped the command.
At this point, you can test the problem site again. If you still get an error, you'll probably need to clear your browser cache.
Clearing Web Browser Cache
Again, the instructions vary based on your web browser. Below are commands for common browsers.
For Google Chrome 15,
Go to Tools | Options | Under the hood | Clear Browsing data| select Empty the cache | Clear browsing data.
For Firefox 8,
Go to Tools | Clear recent history | Select cache | Clear Now
For Internet Explorer 9,
Go to Tools | F12 developer tools | click Cache on toolbar menu | Clear browser cache | Yes
Although this DNS problem resolved around a suspected phishing issue, there are other reasons your DNS may have issues connecting to one of your sites. The best bet is to create a DNS backup plan beforehand and know what to do when things don't work as expected.
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Last Updated (Saturday, 29 September 2012 08:30)