200-301 · Question #877
A network engineer must configure an interface with IP address 10.10.10.145 and a subnet mask equivalent to 11111111.11111111.11111111.11111000. Which subnet mask must the engineer use?
The correct answer is A. /29. The subnet mask 11111111.11111111.11111111.11111000 has 29 bits set to '1', which corresponds to a /29 CIDR notation.
Question
Options
- A/29
- B/30
- C/27
- D/28
How the community answered
(64 responses)- A78% (50)
- B13% (8)
- C6% (4)
- D3% (2)
Why each option
The subnet mask 11111111.11111111.11111111.11111000 has 29 bits set to '1', which corresponds to a /29 CIDR notation.
The binary subnet mask 11111111.11111111.11111111.11111000 contains 29 consecutive '1's starting from the left, directly indicating a /29 CIDR prefix length for the network portion of an IP address.
A /30 mask represents 30 network bits (11111111.11111111.11111111.11111100), which is incorrect for the given binary mask.
A /27 mask represents 27 network bits (11111111.11111111.11111111.11100000), which is incorrect for the given binary mask.
A /28 mask represents 28 network bits (11111111.11111111.11111111.11110000), which is incorrect for the given binary mask.
Concept tested: Subnet mask CIDR notation conversion
Source: https://www.cisco.com/c/en/us/support/docs/ip/routing-information-protocol-rip/13788-3.html
Topics
Community Discussion
No community discussion yet for this question.