nslookup will go and check the dns server to do a forward lookup on the web address given and convert it to an ip address. The dns server is usally provided by the ISP, if the dns server is missing/misconfigured this can be one of the reasons why an internet connection is lost. YOu may also want to try a tracert 66.102.9.147 (this is google IP) tracert will show the route your nslookup request takes to reach its destination, it will also show me if you are using a router and if the requests are passing through it successfuly