OpenDNS DNS servers stopped responding

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sderuiter

February 09, 2014 10:35

Happy OpenDNS user since 2011, using the OpenDNS Deluxe plan for managing my home network.

As of 3 days ago, my machines weren't able to resolve any hosts. I checked to see what the issue might be, but I'm out of solutions.

I can:

1. ping my ISPs IP address and get a response

2. ping 208.67.222.222 and 208.67.220.220 and get a response

3. access 208.69.38.170 (the OpenDNS system status page) in Chrome fine

 

I cannot:

1. access any site  from Chrome (or Safari on iPhone)

 

As far as I can tell, nothing has changed at my ISP.

 

Any hints to what this is causing?

Thanks.

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  rotblitz February 09, 2014 15:30

  It seems your DNS server configuration is broken.

  In case you use Windows, post the complete plain text output of the following commands here:

  nslookup -type=txt  which.opendns.com.

  ipconfig /all

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  sderuiter February 09, 2014 20:31

  Hi,

   

  Problem solved. Due to a security breach (http://www.avm.de/de/News/artikel/2014/angriffe_auf_fritzbox_nachvollzogen.html?linkident=kurznotiert) at AVM, my ISP (xs4all.nl) decided to proactively block ports 53 and 5060. My OpenDNS dashboard told me the exact hour when I stopped reaching OpenDNS, which was around the time the ISP blocked these ports.

  Asking my ISP to unblock them solved this.

  Thanks for you help. 

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  rotblitz February 09, 2014 21:53

  Ah, this makes perfectly sense!  With the exception that port 53 was not reported as an attack target, so blocking it didn't make any sense.
  Port 5060 is for SIP (VoIP), and port 443 is the admin webinterface

  Thanks for the feedback.

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