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Zorluk: OrtaIPv4 Addressing and Subnetting

A network engineer is configuring static host IP addresses for infrastructure devices within the newly assigned network block 10.88.16.0/2010.88.16.0/20. Which of the following IPv4 addresses represents the last valid, usable host address in this subnet?

  1. 10.88.31.25410.88.31.254Cevap
  2. B
    10.88.31.25510.88.31.255
  3. C
    10.88.32.25410.88.32.254
  4. D
    10.88.30.25410.88.30.254

Cevap

10.88.31.25410.88.31.254
For the subnet 10.88.16.0/2010.88.16.0/20, the subnet mask is 255.255.240.0255.255.240.0, giving a block size of 16 in the third octet. The network span is from 10.88.16.010.88.16.0 to 10.88.31.25510.88.31.255. Reserving 10.88.16.010.88.16.0 for the network ID and 10.88.31.25510.88.31.255 for the broadcast address leaves 10.88.16.110.88.16.1 through 10.88.31.25410.88.31.254 as usable host addresses. Therefore, 10.88.31.25410.88.31.254 is the last valid usable host IP.

Adım Adım Çözüm

1
Calculate the subnet mask and third-octet block size for a /20 prefix.
A /20 prefix corresponds to the mask 255.255.240.0255.255.240.0. The block size in the third octet is 256−240=16256 - 240 = 16.
The third octet contains 4 network bits and 4 host bits (24=162^4 = 16).
2
Determine the network boundary and broadcast address.
Starting at network ID 10.88.16.010.88.16.0, adding 16 to the third octet gives the next subnet starting at 10.88.32.010.88.32.0. Thus, the broadcast address is 10.88.31.25510.88.31.255.
The broadcast address is one address before the start of the next subnet.
3
Identify the last usable host IP address.
Subtracting 1 from the broadcast address (10.88.31.255−110.88.31.255 - 1) yields 10.88.31.25410.88.31.254.
The last usable host address is always the IP immediately preceding the subnet broadcast address.

Anahtar Kavram

IPv4 Subnet Host Boundaries and Allocation
Tahmini Süre:1m 15s
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Konular

IPv4 Addressing and Subnetting

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