Resource Records - Quiz Explanation

The answers you selected are indicated below, along with text that explains the correct answers.
 
1. Corporation.com uses the alias mail.corporation.com for the machine named gates.corporation.com. The IP address for this system is 192.168.56.3. Which of the following zone file entries reflects this fact?
Please select the best answer.
  A. mail 192.168.56.3 IN CNAME gates.corporation.com.
  B. IN A 192.168.56.3 gates.corporation.com.
  C. IN PTR 56.168.192
  D. mail IN CNAME gates.corporation.com.
  The correct answer is D. Whenever you want to assign an alias to a system with a previously assigned name, you must use a CNAME entry. The proper syntax is to give the new name, then use IN to show the use of IP as the transport protocol. CNAME allows you to provide the alternative, new name. You then specify the existing name of the server.

2. The corporation.com Internet Service Provider Supernet.net also supplies name service. The server named dns.supernet.net (IP address 111.234.11.154) is a secondary server for the corporation.com network. What is the new NS record you should add to reflect this relationship?
Please select the best answer.
  A. IN NS dns.supernet.net 111.234.11.154
  B. IN NS dns.supernet.net
  C. $IN NS dns.supernet.net
  D. 200 IN NS dns.supernet.net
  The correct answer is B. After providing an IN entry, which refers to the use of IP as the transport protocol, you then use NS to note that the address or machine name is for a DNS server. Finally, you give the name of the machine, or the IP address.

3. You have been assigned to add a host to your network. Its IP address is 192.168.56.205. After configuring this system to participate on your DNS-enabled network, you must add this host to the DNS zone file. Specifically, you must add an address in the forward-lookup zone. The name of the host will be jobs. Which of the entries below is the correct forward-lookup zone entry?
Please select the best answer.
  A. jobs IN A 192.168.56.205
  B. IN A 192.168.56.205 jobs
  C. IN PTR jobs
  D. 192.168.56.205 IN A jobs
  The correct answer is A. After configuring a host, you can establish its identity by first identifying its name (jobs), then show that it is participating in an IP network with IN. Finally, you specify the name to address mapping with A, then give the correct IP address (192.168.56.205).

4. You have just identified the forward-lookup zone for jobs (192.168.56.205). A reverse-lookup zone exists for the subnet (192.168.56.0). Now, which of the following entries given below constitutes a correct reverse-lookup zone entry for jobs?
Please select the best answer.
  A. 200 IN PTR 192.168.56.205
  B. 201 A PTR 192.168.56.205
  C. 205 IN PTR jobs.corporation.com
  D. IN PTR jobs.corporation.com
  The correct answer is C. The 205 entry specifies the IP address that exists on the 56 subnet. The IN record specifies the use of IP as the networking protocol. The PTR entry specifies a reverse-lookup entry. You then specify the name of the system (jobs.corporation.com).