You are a network administrator of college campus network where 25,000 students
ID: 2079970 • Letter: Y
Question
You are a network administrator of college campus network where 25,000 students and 4,000 faculty and staff work. College campus network has approximately 20,000 hosts including desktop computers, laptops and network printers.
A). What would be your approach to assign IP address to 20,000 hosts? Justify your answer?
B). If you have to choose only one class of an IP address college campus network, what class of IP address would you choose? Why?
C). What would you do and/or install to protect the network from external malicious access and attacks?
D). Why do we need two different addresses (MAC and IP addresses) for computer networks? Give scenarios or examples of both where two computers communicate with each other using MAC and IP addresses?
Explanation / Answer
(A) We'll keep all the 20,000 hosts on the same private network with Network address translation(NAT) installed on the gateway so that we can minimise the organisation's cost to purchase public IP addresses. We'll setup a DHCP server on the gateway so that IP addresses can be assigned dynamically to hosts to prevent wastage of IP addresses by static assignment.
(B) Since we have a moderately large number of hosts within the same network we should go for class B IP class as it can support 65534 hosts where 1 IP will be consumed by the gateway and the rest will be available for the 20,000 hosts.
(C) Installing atleast a level 5 firewall on the gateway will provide protection from internal as well as external threats since all the requests and responses will pass through the gateway although a layer 8 firewall like cyber roam is recommended. Additionally its also a great idea to invest in VPN connection if the organisations has the budget as it can improve the security significantly.
(D)We need both MAC and IP addresses as each has its own advantages.IP addressees are used in the network layer to identify hosts within same as well as different networks where as MAC addresses are used at data link layer to identify the hosts within the same network.IP addresses are logically partitioned into network id and host id hence they are very useful for routing but since MAC addresses are mostly random (generated using manufacturer's serial id) , it cannot be used for routing on the other hand MAC addresses are completely unique but two systems with 2 different private networks may have the same IP address. Lets consider an example to see the working of both addresses.
Consider, network 1 having host A and router R1 with IP and MAC addresses pair (I1,M1) and (I2,M2) respectively and network 2 having host B and router R2 with IP and MAC addresses pair (I3,M3) and (I4,M4) respectively. Let's see the process when A wants to send data to B.
(1) A uses ARP to get MAC address of R1 after it determines that B is in a different network and then sends the packet to R1's MAC address with destination IP as I4 .
(2) R1 uses its routing table to determine the network containing I4 and then forwards the packet to R2's IP address.
(3) R2 uses ARP to determine B's MAC address using its IP address I4 and then forwards the data packet to B
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