An enterprise network administrator is assigned the IPv4 network block 192.168.16.0/22 to … — CompTIA Network+

An enterprise network administrator is assigned the IPv4 network block $192.168.16.0/22$ to provision subnets for a new regional office. Using Variable Length Subnet Masking (VLSM) to minimize address waste, subnets are created for the following minimum usable host requirements:

- Department A: $250$ usable host IPs
- Department B: $120$ usable host IPs
- Department C: $60$ usable host IPs
- Department D: $25$ usable host IPs

What is the total number of unallocated IP addresses (including network and broadcast addresses) remaining in the original $192.168.16.0/22$ block after these subnets are assigned?

Cevap: 544 addresses

Cevap

544 unallocated IP addresses remain in the original /22 block.

A /22 block provides

1024

total addresses. By sizing each subnet to the smallest power of 2 that accommodates host requirements plus network and broadcast overhead, the allocations consume

256

(/24),

128

(/25),

64

(/26), and

32

(/27) addresses, totaling

480

addresses. Subtracting

480

from

1024

leaves

544

unallocated addresses.

Adım Adım Çözüm

Determine total capacity of the assigned prefix

A /22 subnet contains

2^{10} = 1024

total IP addresses.

The prefix length of /22 leaves

32 - 22 = 10

host bits.

Calculate required CIDR subnet block size for each department using VLSM rules

Dept A needs 256 IPs (/24); Dept B needs 128 IPs (/25); Dept C needs 64 IPs (/26); Dept D needs 32 IPs (/27).

Each subnet must accommodate the usable hosts plus 2 overhead addresses (network ID and broadcast address), rounded up to the smallest power of 2.

Sum total allocated IP addresses

256 + 128 + 64 + 32 = 480

IP addresses allocated.

Combining block sizes yields the total addresses consumed across all four departmental subnets.

Calculate remaining unallocated IP addresses

1024 - 480 = 544

unallocated IP addresses.

Subtracting allocated addresses from the total block size leaves the unassigned address space.

Anahtar Kavram

VLSM Subnet Block Size Calculation & Host Address Allocation

Soru

Cevap

Adım Adım Çözüm

Anahtar Kavram

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