You have a network 115.64.4.0/22 that you want to create subnets on. The subnets need to support up to 60 hosts each. How many bits would you allocate for the host part of the subnets? How many such subnets can you support?
Try an answer before revealing the guidance below.
Key Concepts
- CIDR
- Usable hosts
- Host bits
- Subnet bits
Answer Approach
- Find the smallest h with 2^h − 2 ≥ 60.
- Convert the host bits to a prefix length.
- Compare with /22 to count borrowed subnet bits.
Full Answer
Answer status: Draft answer (unofficial). Revision notes, not an official marking scheme.
Six host bits give 2^6 − 2 = 62 usable host addresses, enough for 60. That makes each subnet /26. The /22 block contributes four additional prefix bits, so it can be split into 2^4 = 16 such /26 subnets.
Usable hosts = 2^h − 2Subnet count = 2^(26 − 22) = 16Shortcuts: K concepts · A approach · F answer · R reviewed · B bookmark · ← / → previous / next