(A) DNS is used to translate domain name into IP address.
For resolving the query ,first the request is forwarded to local DNS resolver . It checks if it has entry for the domain name in it's DNS cache.If there is no entry ,it is forwarded to root name server and then to Top Level Domain Server if required.
It can be a recursive query in which local DNS server who has received the request will do all the fetching
Or an iterative query, in which instead of fetching out the data ,the server will forward out the referrals to another DNS server.
Most of the ISPs use Recursive DNS query .
Here, the DNS query will be send to it local DNS server . The local DNS server has no entry in it's cache therefore recursive query will be forward out to the other DNS server .
The query will be resolved by the DNS server and will be send to local DNS server which further forward out to device which has generated DNS query (Client PC).
(B) If a network device doesn't know the MAC address of a device but knows the IP address then ARP ( Address Resolution Protocol) is used to find out the MAC address of the device.
First, the ARP request will be broadcast to know the MAC address by the source device
Then, ARP reply will come from the device for which ARP request was destined for . It will be unicast.
In this case , ARP request will be :-
Source IP address-18.104.22.168 (IP address of client)
Source MAC address- CC:DD:EE:22:33:44 (MAC address of client)
Target IP address-22.214.171.124 ( IP address of router X)
Target MAC address - 00:00:00:00:00:00 ( MAC address for router X as it is unknown)
Now, the ARP reply will be sent to client from router X
Source IP address-126.96.36.199 ( IP address of router X)
Source MAC address -DD:EE:FF:33:44:55 (MAC address of router X)
Target IP address-188.8.131.52 ( IP address of client)
Target MAC address- CC:DD:EE:22:33:44 (MAC address of client)
C) When Client sends packet to server then,
Source IP address- 184.108.40.206 (IP address of client)
Destination IP address- 220.127.116.11 (IP address of server)
D) the frames are forwarded within the network on the basis of MAC address . When a packet is send from one network to another ,first it goes the gateway of it's own network and then it is forwarded out by gateway on the basis of it's IP address.
Therefore ,the frame will be destined for it's gateway i.e router Y for server
Source MAC address- AA:BB:CC:00:11:22
Destination MAC address- EE:FF:AA:44:55:66
please answer all questions 2. IP Add: 18.104.22.168 HW Add: EE FF AA:44-55.66 P Add: 22.214.171.124 HW Add: DD.EE FF:33:44:55 A client PC on polyu.edu.hk P Add: 126.96.36.199 HW Add: CC DO EE:22...