A network administrator is assigning a private IPv4 host address within the 172.16.0.0/12 … — Cisco CCNA

A network administrator is assigning a private IPv4 host address within the $172.16.0.0/12$ range for a branch office subnet defined as $172.30.50.16/28$ . Which IPv4 address is a valid usable host address for a device in this subnet?

$172.30.50.25$ Answer
B
$172.30.50.16$
C
$172.30.50.31$
D
$172.32.50.20$

Answer

The address

172.30.50.25

is a valid usable host IPv4 address within the

172.30.50.16/28

subnet.

The subnet

172.30.50.16/28

has a block size of

16

addresses (

2^4

), covering

172.30.50.16

through

172.30.50.31

. Subtracting the network address (

172.30.50.16

) and broadcast address (

172.30.50.31

) leaves a usable host range of

172.30.50.17

172.30.50.30

. The address

172.30.50.25

lies within this valid host range and is within the RFC 1918 private block (

172.16.0.0/12

Step-by-Step Solution

Determine the network properties for

172.30.50.16/28

/28

subnet mask has

32 - 28 = 4

host bits, yielding a block size of

2^4 = 16

The block size dictates the increment between subnets.

Identify the network address, broadcast address, and usable host range.

Network Address:

172.30.50.16

; Broadcast Address:

172.30.50.31

; Usable Host Range:

172.30.50.17

172.30.50.30

The network address is the first address in the block, and the broadcast address is the last address in the block.

Verify RFC 1918 private address range compliance and match against options.

The range

172.16.0.0/12

spans

172.16.0.0

172.31.255.255

. The address

172.30.50.25

is both within the RFC 1918 block and within the usable host range

172.30.50.17

172.30.50.30

Only valid usable host addresses within the private range can be assigned to host interfaces.

Key Concept

IPv4 Subnet Boundaries and RFC 1918 Private Addressing

Question

Answer

Step-by-Step Solution

Key Concept

Common Mistakes

Topics

More questions from this topic