Introduction to DNS
All answers must be typed!
This section helps you understand about DNS nameserver. Please note that these questions are tested for Windows OS. You may want to read the slides first.
A- Using nslookup command (nslookup ucc.edu.gh) answer the following questions: (note that if you get timeout for any of the commands, that is because your connection is intermittent; so try again!) You can use Trace IP site to answer many of the following questions.
- What is the IP address for ucc.edu.gh?
- What is the IP address of the DNS server of ucc.edu.gh? Can you tell the name of the DNS server machine (DNS nameserver)?
- What is the significance of doing nslookup ucc.edu.gh 184.108.40.206 ? What is 220.127.116.11?
- What is the IP address of host resolver1.opendns.com?
- Where is resolver1.opendns.com machine physically located at? What is its significance?
- What is the average round trip time (RTT) when you ping UCC DNS nameserver? How is it compared to pinging google.com? What is the average round trip time (RTT) when you ping your OWN computer? Tabulate the ping results for the three cases. In each case specify the RTT.
- What is the IP address of www.ucc.edu.gh? (you can use -querytype=ns option of nslookup command. Do you remember what is -querytype=ns is used for? What is the actual host name of the web server www.ucc.edu.gh? (read about DNS Records)
- If you want to see how many hops are between your machine and www.ucc.edu.gh you can use the traceroute (tracert in wondows) command? Make sure you know how it works! How many countries your packet is traveling through?
- Use visual traceroute to specify how many hops are between your machine and www.ucc.edu.gh. What is strange about this routing? NOTE: You can download visual router on Ubuntu.
- While In C:\ prompt, type nslookup. At the > prompt type >set debug. Then, type >www.ucc.edu.gh. When you receive the response (ANSWER) how many non-authoritative or authoritative DNS nameservers can resolve request about TLD gh?
B- Complete the Wireshark below:
- Complete the Wireshark DNS Example and answer all the questions. Download dns_sime_query if needed
Extra: If you like to learn more do teh following (Do not turn this part in)
Answer the following questions:
- How many DNS root-servers exist around the globe? You can use http://public-root.com/root-server-check/index.htm
- What is the difference between ccTLD and gTLD? Give an example for each.
- What command will you use to find out the host name for IP address 18.104.22.168?
- Does dig command work on Windows machines?
- Read the information on this link: http://help.slamdot.com/idx/0/057/What-are-the-types-of-DNS-records. What is the purpose of NS and A records?
- What is FQDN?
- Which port is dedicated to DNS application?
- What are DNS common software?
More Extra Questions:
- Read Part I of the DNS exercise. Complete part II and answer all the questions. You can obtain a trail version of VisualRoute. You can also use traceroute command.
- As for routing this is an easy tutorial on Netstat.