Case Project 11-1: Configuring DHCP for a New Subnet CSM Tech Publishing has exp
ID: 3724873 • Letter: C
Question
Case Project 11-1: Configuring DHCP for a New Subnet CSM Tech Publishing has expanded its network from one subnet to two subnets and is putting 200 computers on the new subnet, with plans for adding up to 100 more comput- ers over the next few years. Currently, it’s using DHCP for the existing subnet and has a scope configured with start address 172.16.1.1 and end address 172.16.1.200 with a pre- fix length of 24. The DHCP server is in the main distribution facility where the router is placed to route between the subnets. The current DHCP server runs Windows Server 2012 R2, is performing well, and has plenty of unused computing resources (CPU, memory, and so forth). You need to configure DHCP for the new subnet at the lowest cost possible. What do you recommend for adding DHCP services to the new subnet? Propose a DHCP configuration and the scope’s start and end addresses and prefix length for the new subnet.
Explanation / Answer
Solution :-
The DHCP configuration with start address 172.16.1.1 and end address 172.16.1.200 and the subnet mask is 255.255.255.0 that is prefix length of 24. That is the network can be represented as172.16.1.0/24
In this subnet total 254 usable IP addresses available from which 200 IP addresses already in use. Now there is requirement of 200 additional IP address space and 100 IP addresses for the future, so total 300 IP address space is required for the new subnet.
To fulfil this requirement we use the Superscoping in the DHCP configuration. In the Superscoping the the existing subnet will not be changed and additional logical subnet with required address space can be created.
The Existing subnet is 172.16.1.0/24 and start address 172.16.1.1 and end address 172.16.1.200
Now we create the additional subnet on the same DHCP server. The new network is as follows -
Network address - 172.16.2.0/23
Subnet mask - 255.255.254.0
Start Address - 172.16.2.1
End Address - 172.16.3.254
Broadcast address - 72.16.3.255
Description -
In this DHCP configuration of the new subnet, the mask is 255.255.254.0 that is the prefix length is 23. It means 23 bits used for network and 9 bits for the host. So the IP address space is 29 = 512. And the requirement is 300 IP addresses therefore this new subnet is sufficient for the requirement.
In the superscoping both the subnets behaves as different networks and needs some additional configuration on router to interconnection.