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Zorluk: OrtaIPv4 Addressing and Subnetting

A network technician is configuring an IP addressing plan for an IoT security segment that requires static IP assignments for 6262 security cameras and 22 default gateway interfaces. Which CIDR prefix length represents the most space-efficient IPv4 subnet mask that satisfies this requirement?

  1. /25Cevap
  2. B
    /26
  3. C
    /27
  4. D
    /24

Cevap

/25
The total number of IP addresses required is 62+2=6462 + 2 = 64. Using the usable host formula 2n−22^n - 2, a subnet with n=6n = 6 host bits provides 26−2=622^6 - 2 = 62 usable addresses, which is not enough. Increasing to n=7n = 7 host bits yields 27−2=1262^7 - 2 = 126 usable host addresses. The resulting prefix length is 32−7=2532 - 7 = 25, making the /25 prefix length the most space-efficient valid choice.

Adım Adım Çözüm

1
Calculate total usable host addresses required
62 cameras + 2 gateway interfaces = 64 usable host addresses
Both endpoint devices and gateway interfaces require individual usable IP addresses within the subnet.
2
Apply the usable host formula (2n−2≥642^n - 2 \ge 64)
For n=6n = 6 host bits, 26−2=622^6 - 2 = 62 usable hosts (insufficient). For n=7n = 7 host bits, 27−2=1262^7 - 2 = 126 usable hosts (sufficient).
Two IP addresses in every IPv4 subnet are reserved for the network ID and the broadcast address, so 2 must be subtracted from total addresses.
3
Determine the CIDR prefix length
32−7=2532 - 7 = 25, corresponding to /25 prefix length
Subtracting the required host bits from 32 total IPv4 bits gives the prefix length.

Anahtar Kavram

IPv4 Subnetting and Usable Host Calculation
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Konular

IPv4 Addressing and Subnetting

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