dns server not responding

I had the error: "the dns server is not responding" on my laptop ( win 7-connected wirelessly)on trying to connect to the web. I also tried to log on on my desktop computer ( win xp- wired connection) without success. However shortly afterwards ( few minutes) both computers connected ok. . This happened more than once. What I want to know is where is the fault might be...my router, service provider or my computers ( both at the same time!!

http://theos.in/windows-xp/free-fast-public-dns-serv...

Start with checking your ISP's service status, your exchange status etc. Sounds more like something on their side of things, unless this problem has occurred a lot over a long period of time (which would indicate your connection).