Which two of the following IPv4 addresses come from the RFC 1918 private ranges? (Choose two.)
LPIC-1 Exam 102-500, objective 109. Networking fundamentals medium
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The options
Choose 2.
Not correct 172.15.8.9
Wrong. The private block is 172.16.0.0/12, which spans 172.16.0.0 to 172.31.255.255. 172.15.x.x sits just below it and is public.
Not correct 192.169.4.1
Wrong. Only 192.168.0.0/16 is private. 192.169.x.x is one step outside and is publicly routable.
Correct 10.200.14.3
Correct. The entire 10.0.0.0/8 block is private, covering 10.0.0.0 to 10.255.255.255.
Correct 172.20.0.5
Correct. 172.20.x.x falls inside 172.16.0.0/12 and is therefore private.
Not correct 169.254.10.2
Wrong for this question. 169.254.0.0/16 is the link-local (APIPA) range a host self-assigns when no DHCP server answers. It is not routable, but it is not one of the RFC 1918 private ranges.
Why
The three private ranges are 10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16. The 172 block is the one most often misremembered: it is 172.16 through 172.31 inclusive, not 172.16 through 172.16.255 and not all of 172.x. Addresses from these ranges are never routed on the public internet and normally reach it through NAT. Seeing a 169.254 address on an interface is a strong hint that DHCP failed.
Where this comes from
- Cited
- LPI exam objective 109.1
- What it says
- Know the private IPv4 address ranges reserved for internal networks.
Practise this
Reading one question is not practice. The trainer will draw a set from objective 109 and space the ones you get wrong.