IP addresses are categorized as either public or private. According to the IANA (Internet Assigned Numbers Authority), the following are reserved for private use:

10.0.0.0 to 10.255.255.255 (Class A Private)

172.16.0.0 to 172.31.255.255 (Class B Private)

192.168.0.0 to 192.168.255.255 (Class C Private)

Any IP outside of these ranges is considered public and routable on the global internet.

Evaluation of each option:

A. 172.168.254.2 → This is in the 172.16.0.0 – 172.31.255.255 range → Private

B. 172.28.73.21 → Also falls in the same private 172.16.0.0/12 range → Private

C. 11.63.72.21 → Outside all private ranges → Public✅

D. 10.110.50.37 → In the 10.0.0.0/8 range → Private

E. 192.168.0.1 → In the 192.168.0.0/16 private range → Private

Extract from René Meneses MTCNA Study Guide:

“Private IP ranges include 10.0.0.0/8, 172.16.0.0/12, and 192.168.0.0/16. These are non-routable over the public internet.”

Extract from Terry Combs Notes:

“Only IPs outside of the above ranges are considered public and routable. Watch out for 172.X.X.X — not all are public; only 172.0.0.0–172.15.255.255 and 172.32.0.0+ are public.”

MikroTik Wiki – IP Addressing Reference:

“Private addresses are not globally routable. They are used inside local networks and must be NATed for internet access.”

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