2. (20 points) Network Address Translation (NAT) A. (5 points) Explain why NAT c
ID: 3920887 • Letter: 2
Question
2. (20 points) Network Address Translation (NAT) A. (5 points) Explain why NAT can be viewed as a means of extending the utilization of IPv4 addresses. B. (5 points) Name an additional benefit ofusing NAT, besides extending the utilization of IPv4 addresses. C. (10 points) Below is the translation table in a NAT router. The NAT router has public IP Address 64.233.169.104 For the incoming response packet (Gublic network side) to the request from private node 172.18.3.2 in row 2 of the table Write the source IP Address, and Port; destination IP Address and Port destination source ExternalExternal Transport port 80 80 Private protocol TCP address 172.18.3.125.8.3.280 172.18.3.2 port 1400 1401Explanation / Answer
2.a).The number of IPv4 addresses is very limited.if we assign a single IPv4 address to each host in need then sooner or later we will run out of the IPv4 addresses because it needs to be unique throughout the world.NAT prevent this by providing the private ip address to the host within the network and perform proper address translation when a host in network wants to send data out of the network.
The private IP address assigned by NAT to the host within the network is unique but in different NAT networks these private IP address can be same.only unique thing that the two or more NAT network posses is the set of public IP address.due to this,the public IP addresses are very effectively used because they are not assigned to any specific host but to NAT and the number of public IP addresses assigned to NAT is very low as compared to the number of hosts in the network.
Whole process works like this-
1.Firstly the admin assign the private addresses to the hosts within the network.
2.When any host wants to send data outside it is firstly directed to the NAT.NAT converts the private IP address in that packet to public IP address and maintains a table of public IP addresses assigned to any specific Hosts within its vicinity.
3.When response comes from receiver.NAT converts the public IP address into the private IP address based on the table it had maintained.
4.Based on the private IP address obtained from table,it is forwarded to the corresponding host.
2.b).NAT has other benefits besides extending the use of the IPv4 addresses like
NAT acts as layer of security kinda like a firewall.since every packet into the network has to pass through it the NAT can filter out the packets which are spams,malicious or anything harmful to the network based on the table it had maintained.
2.c).source Ip address = address of the host who is send the packet to the network. = 25.8.3.2
source port = 80
destination IP address = public address of the NAT = 64.233.169.104
destination port = same as private port = 1401
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