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GSEC · Question #363

Which of the following is a private, RFC 1918 compliant IP address that would be assigned to a DHCP scope on a private LAN?

The correct answer is C. 10.254.1.50. RFC 1918 defines three specific private IP address ranges, and only addresses falling within 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16 qualify as valid RFC 1918 private addresses.

Networking and Core Concepts

Question

Which of the following is a private, RFC 1918 compliant IP address that would be assigned to a DHCP scope on a private LAN?

Options

  • A127.0.0.100
  • B169.254.1.50
  • C10.254.1.50
  • D172.35.1.100

How the community answered

(29 responses)
  • A
    3% (1)
  • B
    7% (2)
  • C
    76% (22)
  • D
    14% (4)

Why each option

RFC 1918 defines three specific private IP address ranges, and only addresses falling within 10.0.0.0/8, 172.16.0.0/12, or 192.168.0.0/16 qualify as valid RFC 1918 private addresses.

A127.0.0.100

127.0.0.100 belongs to the 127.0.0.0/8 loopback range reserved for local host communication, which is not one of the private LAN ranges defined by RFC 1918.

B169.254.1.50

169.254.1.50 is in the APIPA range 169.254.0.0/16, which is defined by RFC 3927 for link-local addressing, not by RFC 1918.

C10.254.1.50Correct

The address 10.254.1.50 falls within the 10.0.0.0/8 range (10.0.0.0 to 10.255.255.255), which is one of the three private address blocks explicitly defined by RFC 1918. This range is commonly assigned in enterprise and home LAN DHCP scopes and is not routable on the public internet.

D172.35.1.100

172.35.1.100 falls outside the RFC 1918 private range for 172.x.x.x, which only spans 172.16.0.0 to 172.31.255.255 - making 172.35 a public, routable address.

Concept tested: RFC 1918 private IP address ranges

Source: https://www.rfc-editor.org/rfc/rfc1918

Topics

#RFC 1918#private IP addresses#DHCP#network addressing

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