A network administrator is provisioning a dedicated IPv4 subnet for a store's point-of-sal… — CompTIA Network+

A network administrator is provisioning a dedicated IPv4 subnet for a store's point-of-sale terminals using the network address block $172.16.100.0/22$ . Which of the following represents the first usable host IP address within this subnet?

$172.16.100.1$ Answer
B
$172.16.100.0$
C
$172.16.101.1$
D
$172.16.96.1$

Answer

The first usable host IP address in the

172.16.100.0/22

subnet is

172.16.100.1

For the network block

172.16.100.0/22

, the subnet mask is

255.255.252.0

. The network boundary starts at

172.16.100.0

. Because the network address cannot be assigned to an endpoint, the first usable host IP address is obtained by adding 1 to the network address, yielding

172.16.100.1

Step-by-Step Solution

Determine the network address and block size for a /22 prefix.

A /22 mask (

255.255.252.0

) has a block size of

256 - 252 = 4

in the third octet. Since

100

is a multiple of

4

172.16.100.0

is the valid network boundary.

Identifying the network ID establishes the starting boundary of the subnet.

Calculate the first usable host IP address by adding 1 to the host portion of the network ID.

Network ID

172.16.100.0

1

172.16.100.1

The network address itself cannot be assigned to hosts, so the first usable host IP is immediately after the network ID.

Key Concept

IPv4 Subnet Boundaries and Usable Host Range

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