1. What are the three classes of DNS servers? Describe each. 2. Assume the follo

Question

1. What are the three classes of DNS servers? Describe each.

2. Assume the following email scenerio: Tom uses his g-mail web account to write and send a message to his boss Jane. At work, Jane pops her email messages to her desktopby using POP3. There are three steps necessary to get the message from Tom's host to Jane's host. Describe these three steps and for each step, identify the specific applicationlayer protocal that is utilized.

3. Consider accessing your email with POP3. Suppose you have configured your pop mail client to operate in the download-and-keep mode.Complete the following:

c:list

s:1 765

s:2 226

s:

c:retr 1

s:how are you

s: ...bye

s:.

?

Explanation / Answer

Generaaly DNS Server provides for mainly three types of classes which are called as zones.They are:

Primary zone:
In this type of class, DNS server is the main and primary source for information, typically it stores the master data in a local file.If the file is stored in any file, By default this type of zone file is named zone_name.dns.

Secondary zone
In this type, DNS server is a secondary source for information. Class or zone at this type of server should be obtained from remote DNS computer which hosts the zone. This type of DNS server contains network access with remote DNS server. Because of accessing remote and is a secondary zone we cannot store in AD DS.

Stub zone
In this type,DNS server provides information regarding authoritative name servers only. The classes at this server should be obtained from another DNS server which hosts. This type also must have network access.

3)As per given instrcutions,if the client receives the messages then they should stay on the server. Afterthat,if he/she hits quit command, the server automatically stores and updates messages in the mailbox.So that the add the following lines to complete.

C: retr 2
S: Some information
S: .
C: quit
S: +OK POP3 server signing off

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