CyberCertPrepNetwork FundamentalsIP Addressing & SubnettingEASYFree question
What does the term 'private IP address' mean, and which three ranges are defined as private by RFC 1918?
- A.Private IPs are encrypted addresses used within corporate VPNs only
- B.Private IP addresses are ranges reserved for internal (non-internet) use. RFC 1918 defines: 10.0.0.0/8 (Class A), 172.16.0.0/12 (Class B, covers 172.16.0.0-172.31.255.255), and 192.168.0.0/16 (Class C). These are not routed on the public internet and require NAT for internet access
- C.Private IPs are the same as APIPA (169.254.x.x) addresses
- D.RFC 1918 defines one private range: 192.168.0.0/24
Why B is correct
RFC 1918 (Address Allocation for Private Internets) defines three private IPv4 ranges: (1) 10.0.0.0/8: 10.0.0.0-10.255.255.255 (16.7M addresses). (2) 172.16.0.0/12: 172.16.0.0-172.31.255.255 (1.05M addresses - note this covers /12, not just /16). (3) 192.168.0.0/16: 192.168.0.0-192.168.255.255 (65,536 addresses). ISPs filter these ranges and do not route them on the public internet. Hosts with private IPs need NAT/PAT to reach the internet.
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