In this lab we learn about Domain Name System (DNS) it is used to map the name to the IP address. This lab is implemented using the Wireshark tool. For getting the IP address of the DNS server command nslookup is used in the command line interface.
The host can be identified in two ways
1. By IP address
2. By host name
Generally it is easy to remember the name of the host than to remember the IP address of the each website (for example we access google the name google.com but not by IP address). But the routers cannot understand the names it can only understand the IP addresses hence there is a requirement to convert the host name to IP address for this translation purposes we use Domain Name System it is implemented as a hierarchy. In the hierarchy, the top…show more content… This entire process of conversion takes place in six steps
1. Request information
2. Ask the recursive DNS servers
3. Ask root name servers
4. Ask top level domain name servers
5. Ask the authoritative DNS servers
6. Retrieve record
7. Receive answer
The entire process is very fast and it takes milliseconds to complete.
There are 13 DNS servers most of which are present in North America most of which are replications of each other for the better security and reliability. Queries related to the mail and web servers are answered by the authoritative DNS servers.
There are two types of authoritative DNS servers
1. Master server: it has the copies of all zone records
2. Slave server: it has the copy of the primary server
If the host manager makes changes to the primary server and the contents in slave server changes automatically by the updating mechanisms of DNS.
Records and messages are included in DNS. The DNS messages are of two types query message and the response message they have same frame format. Their frame format is as
