Which is the valid IP address range that can be assigned to hosts on the subnet that includes the address
172.16.4.6/23?
A.
172.16.2.1 – 172.16.4.254
B.
172.16.3.1 – 172.16.5.254
C.
172.16.4.1 – 172.16.5.254
D.
172.16.4.1 – 172.16.4.254
Explanation:
172.16.4.1 – 172.16.5.254 is the valid IP address range that can be assigned to hosts on the subnet that
includes the address 172.16.4.6/23.
To determine the range of addresses that can be assigned in a subnet, you must first determine the network ID
and broadcast address of the subnetwork. All addresses that can be assigned to hosts will lie between these
two endpoints. The network ID can be obtained by determining the interval between subnet IDs. With a 23-bit
mask, the decimal equivalent of the mask will be 255.255.254.0. The interval between subnets can be derived
by subtracting the value of the last octet of the mask from 256. In this case that operation would be 256 – 254.
Therefore, the interval is 2, and it is applied in the third octet where the subnet mask ends.
The first network ID will always be the classful network you started with (in this case 172.16.0.0). Then each
subnetwork ID will fall at 16-bit intervals as follows:
172.16.0.0
172.16.2.0
172.16.4.0
172.16.6.0
At 172.16.6.0 we can stop because the address that we are given in the scenario, 172.16.4.6, is in the network
with a subnet ID of 172.16.4.0. Therefore, since the broadcast address for this network will be 1 less than the
next subnet ID, or 172.16.5.255, the valid range is 172.16.4.1 – 172.16.5.254.All the other options are incorrect because these are not valid IP address ranges for this scenario.
Objective:
Network Fundamentals
Sub-Objective:
Apply troubleshooting methodologies to resolve problemsCisco > Technology Support > IP > IP Routing > Design TechNotes > IP Addressing and Subnetting for New
Users > Document ID: 13788 > Understanding IP Addresses