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Zorluk: OrtaIPv4 Addressing and Subnetting

A network administrator is assigned the IPv4 address block 10.50.0.0/2210.50.0.0/22 to provision subnets for an enterprise IP telephony deployment. Each subnet requires support for at least 5050 usable host IP addresses. If the administrator subnets the entire 10.50.0.0/2210.50.0.0/22 block using a uniform prefix length that meets this host requirement with minimal wasted host space, how many total subnets can be created?

Cevap: 16 subnets

Cevap

16 subnets can be created from the block.
To support at least 50 usable host IP addresses per subnet, 6 host bits are needed (262=622^6 - 2 = 62 usable IPs), which corresponds to a /26 prefix length (326=2632 - 6 = 26). Borrowing bits from the parent /22 prefix to create /26 subnets uses 2622=426 - 22 = 4 subnet bits, resulting in 24=162^4 = 16 total subnets.

Adım Adım Çözüm

1
Calculate the number of host bits required for 50 usable IP addresses
6 host bits are required
The formula for usable host IPs is 2h22^h - 2. With h=5h = 5, 252=302^5 - 2 = 30 hosts (insufficient). With h=6h = 6, 262=622^6 - 2 = 62 usable hosts, which satisfies the requirement of at least 50 hosts.
2
Determine the new subnet prefix length
The prefix length is /26
Subtracting the 6 host bits from the 32-bit IPv4 address space yields 326=2632 - 6 = 26.
3
Calculate the number of subnets derived from the parent /22 block
16 subnets
Subtracting the original prefix (/22) from the new prefix (/26) gives 2622=426 - 22 = 4 subnet bits. Borrowing 4 bits produces 24=162^4 = 16 subnets.

Anahtar Kavram

Subnet sizing and calculation of total subnets created using FLSM from a CIDR block.
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