I think there is a "@" missing in the zone file (etc/bind/example.com.zone for Ubuntu) just before IN NS localhost.;
without it I was always getting responses from the web.
Hi, Thanks for the input. This is an interesting issue with the zone file since the file is white space sensitive. If the first charcter is a white space then the "@ is assumed, if not then the NS record is not processed correctly. In the example file in the lab should have spaces to line up the elements in the file. Either option is correct but it may be easier to read with the @" in the first character position.