4.(8 points) The useful tool available on UNIX and Linux hosts is often used by

Question

4.(8 points) The useful tool available on UNIX and Linux hosts is often used by the DNS administrators to explore the hierarchy of DNS servers and troubleshoot DNS problems. For this problem, you may either use your own computer running UNIX/Linux/Mac OS if you have one, or use the server.

First, man the dig command, and then run it to answer the following questions: what is the IP address of gaia.cs.umass.edu? Show the list of names of DNS servers that are involved in answering your query.

Justify your answers by redirecting the output(s) of your command(s) to a text file (please name it dig_output.txt) and attaching it to your submission.

Explanation / Answer

Q what is the IP address of gaia.cs.umass.edu?
128.238.245.34

Q Show the list of names of DNS servers that are involved in answering your query.
a.root-servers.net
E.GTLD-SERVERS.NET
ns1.umass.edu(authoritative)
First command: dig +norecurse @a.root-servers.net any gaia.cs.umass.edu
;; AUTHORITY SECTION:
edu. 172800 IN NS E.GTLD-SERVERS.NET.
edu. 172800 IN NS A.GTLD-SERVERS.NET.
edu. 172800 IN NS G3.NSTLD.COM.
edu. 172800 IN NS D.GTLD-SERVERS.NET.
edu. 172800 IN NS H3.NSTLD.COM.
edu. 172800 IN NS L3.NSTLD.COM.
edu. 172800 IN NS M3.NSTLD.COM.
edu. 172800 IN NS C.GTLD-SERVERS.NET.
Among all returned edu DNS servers, we send a query to the first one.
dig +norecurse @E.GTLD-SERVERS.NET any gaia.cs.umass.edu
umass.edu. 172800 IN NS ns1.umass.edu.
umass.edu. 172800 IN NS ns2.umass.edu.
umass.edu. 172800 IN NS ns3.umass.edu.
Among all three returned authoritative DNS servers, we send a query to the first one.
dig +norecurse @ns1.umass.edu any gaia.cs.umass.edu
gaia.cs.umass.edu. 21600 IN A 128.119.245.12

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