JN0-102 · Question #297
You have been allocated a /22 network. How many usable hosts are available?
The correct answer is C. 1022. A /22 network mask provides 10 host bits, which totals 1024 possible IP addresses, but only 1022 of these are available for usable hosts.
Question
You have been allocated a /22 network. How many usable hosts are available?
Options
- A510
- B512
- C1022
- D1024
How the community answered
(18 responses)- A6% (1)
- B11% (2)
- C83% (15)
Why each option
A /22 network mask provides 10 host bits, which totals 1024 possible IP addresses, but only 1022 of these are available for usable hosts.
510 usable hosts would correspond to a /23 network, which has 9 host bits.
512 represents the total number of addresses for a /23 network, not usable hosts.
A /22 network has 32 - 22 = 10 host bits. The total number of addresses is 2^10 = 1024. Subtracting the network address and broadcast address leaves 1024 - 2 = 1022 usable host addresses.
1024 represents the total number of addresses for a /22 network, not usable hosts.
Concept tested: Calculating usable hosts in a CIDR block
Source: https://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/13788-3.html
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