A network administrator is assigning an IP address to a newly deployed web server. The def… — Cisco CCNA

A network administrator is assigning an IP address to a newly deployed web server. The default gateway interface for the server's subnet is configured with the IP address $172.20.108.1$ and a subnet mask of $255.255.252.0$ . Which of the following IPv4 addresses is a valid usable host address on the same subnet as the default gateway?

$172.20.110.50$ Answer
B
$172.20.111.255$
C
$172.20.112.1$
D
$172.32.109.10$

Answer

The IP address

172.20.110.50

is a valid usable host address on the

172.20.108.0/22

subnet.

The subnet mask

255.255.252.0

(/22) establishes a block size of

4

in the third octet (

256 - 252 = 4

). For the default gateway IP

172.20.108.1

, the subnet network address is

172.20.108.0/22

, giving a usable host range of

172.20.108.1

172.20.111.254

and a broadcast address of

172.20.111.255

. The IP address

172.20.110.50

falls directly within this valid host range.

Step-by-Step Solution

Determine the subnet block size in the third octet

A subnet mask of

255.255.252.0

(/22 prefix length) leaves

2

host bits in the third octet. The block size is calculated as

256 - 252 = 4

Subnet boundaries in the third octet occur in increments of

4

Calculate the network address, broadcast address, and host range

Since

108

is a multiple of

4

(

4 \times 27 = 108

), the network address is

172.20.108.0/22

. The next subnet starts at

172.20.112.0

, making the broadcast address

172.20.111.255

The broadcast address is one integer below the next subnet's network address.

Identify the usable host range and evaluate candidate IP addresses

The usable host IP range is from

172.20.108.1

through

172.20.111.254

. The IP address

172.20.110.50

lies within this range.

Any IP strictly between the network ID and broadcast ID can be assigned to host interfaces.

Key Concept

IPv4 Subnet Masking and Usable Host Range Calculation

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