Lab 6.2.1 Observing DNS Name Resolution
Step 1: Observe DNS conversion
a. Click the Start button, select Run, type cmd, and then click OK. The command prompt window appears.
b. At the command prompt, type ping www.cisco.com. The computer needs to translate www.cisco.com into an IP address so it knows where to send the Internet Control Message Protocol (ICMP) packets. Ping is a type of ICMP packet.
c. The first line of the output shows www.cisco.com converted to an IP address by DNS. You should be able to see the effect of DNS even if your school has a firewall that prevents pinging, or if Cisco has prevented people from pinging their web server.
d. Which IP address is shown on the screen?
Jawaban : 126.96.36.199
e. Is it the same as the one shown in the figure? Why do you think this occurred?
Jawaban : Ya. www.cisco.com adalah domain name systemnya sedangkan 188.8.131.52 adalah alamat fisiknya.
f. Work together with another student and discuss one or two other instances (besides the ping command) in which the computer would use DNS.
Step 2: Verify DNS operation using the nslookup command
a. At the command prompt, type the nslookup command.
b. What is the default DNS server being used?
Jawaban : ChaceDNS-JKT2.telkom.net.id
c. Notice how the command prompt changed. This is the NSLOOKUP prompt. From this prompt, you can enter commands related to DNS.
d. At the prompt, type ? to see a list of all the available commands that you can use in NSLOOKUPAddress: 184.108.40.206 mode.
e. Write three commands that you can use with NSLOOKUP
f. At the NSLOOKUP prompt, type www.cisco.com.
g. What is the translated IP address?
Jawaban : 220.127.116.11
h. Is it the same as the IP address shown with the ping command?
Jawaban : Tidak
i. At the prompt, type the IP address of the Cisco web server that you just found. You can use NSLOOKUP to get the domain name of an IP address if you do not know the URL. Using the previous procedures, find an IP address associated with www.google.com.
Jawaban : 18.104.22.168, 22.214.171.124, 126.96.36.199, 188.8.131.52, 184.108.40.206, 220.127.116.11
Step 3: Identify mail servers using the nslookup command
a. At the prompt, type set type=mx to have NSLOOKUP identify mail servers.
b. At the prompt, type www.cisco.com.
c. What is the primary name server, the responsible mail address, and the default Time to Live (TTL)?
Jawaban : e144.cd.akamaiedgenet
d. At the prompt, type exit to return to the regular command prompt.
e. At the prompt, type ipconfig /all.
f. Write the IP addresses of all the DNS servers that your school uses.
Jawaban : IP address: 18.104.22.168 dan DNS server: 22.214.171.124 dan 126.96.36.199
g. Type exit to close the command prompt window.
Step 4: Reflection
a. If your school did not have a DNS server, what effect would this have on your use of the Internet?
Jawaban : Request time out.
b. Some companies do not dedicate a single server for DNS. Instead, the DNS server provides other functions as well. Which functions do you think might be included on a DNS server? Use the ipconfig/all command to help you with this.