How The Internet DNS works

foo.bar.edu

ns.bar.edu

Who is www.cs.jhu.edu ?

Do I know www.cs.jhu.edu ? NO

Do I know DNS for cs.jhu.edu ? NO

Do I know DNS for jhu.edu ? Yes 128.220.1.5

Who is www.cs.jhu.edu ?

ns.jhu.edu

128.220.1.5

Do I know www.cs.jhu.edu ? NO

Do I know DNS for cs.jhu.edu ? Yes 128.220.221.5

ns.cs.jhu.edu

128.220.221.5

Do I know www.cs.jhu.edu ? Yes 128.220.221.1

cs.jhu.edu can be resolved by 128.220.221.5

Who is www.cs.jhu.edu ?

www.cs.jhu.edu is 128.220.221.1

www.cs.jhu.edu is 128.220.221.1

HTTP request: get http://www.cs.jhu.edu/

HTTP response

www.cs.jhu.edu

128.220.221.1

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