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CCNPRouting

Do you actually understand Cisco prefix lists?

Prefix lists trip up tons of CCNP Enterprise candidates. Drop your answer in the comments!

The question

What does `ip prefix-list P permit 10.0.0.0/8 ge 16 le 24` match?
  • A10.0.0.0/8 with mask /16 to /24correct
  • B10.0.0.0/8 with mask /8 to /24
  • COnly exact /16 or /24 masks in 10/8

The answer

A 10.0.0.0/8 with mask /16 to /24

The initial slash-8 defines the network bits, while ge and le define the allowed mask length range. Watch out: slash-8 itself is excluded here. Follow for tomorrow's rep.

Exam tip

Read what the question is actually asking before looking at the options. The wrong answers here are ones candidates genuinely pick — each is true of something adjacent, just not of what was asked.