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Which of these is a private IPv4 range reserved by RFC 1918?

172.16.0.0 to 172.31.255.255 is private, along with 10.0.0.0/8 and 192.168.0.0/16.

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  1. 172.32.0.0 to 172.47.255.255
  2. 192.169.0.0 to 192.169.255.255
  3. 172.16.0.0 to 172.31.255.255 ✔

Why: RFC 1918 reserves three private blocks: 10/8, 172.16/12 and 192.168/16. The 172 block stops at 172.31, and the 192 block must be 192.168. The wrong choices are near misses.

Huh, didn't know that: RFC 1918 says IANA reserved three blocks of address space for private internets.

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References

Answer: 172.16.0.0 to 172.31.255.255. RFC 1918 reserves three private blocks: 10/8, 172.16/12 and 192.168/16. The 172 block stops at 172.31, and the 192 block must be 192.168. The wrong choices are near misses.

  1. RFC 1918 www.rfc-editor.org/rfc/rfc1918
    172.16.0.0 - 172.31.255.255 (172.16/12 prefix)
    Checked 2026-10-10.
  2. RFC 1918 www.rfc-editor.org/rfc/rfc1918
    The Internet Assigned Numbers Authority (IANA) has reserved the following three blocks
    Checked 2026-10-10.

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