JN0-102 · Question #362
What is the subnet mask for the 172.45.32.6/19 address?
The correct answer is A. 255.255.224.0. An IP address with a /19 CIDR prefix, such as 172.45.32.6/19, corresponds to a subnet mask of 255.255.224.0.
Question
What is the subnet mask for the 172.45.32.6/19 address?
Options
- A255.255.224.0
- B255.255.240.0
- C255.224.0.0
- D255.240.0.0
How the community answered
(54 responses)- A87% (47)
- B2% (1)
- C7% (4)
- D4% (2)
Why each option
An IP address with a /19 CIDR prefix, such as 172.45.32.6/19, corresponds to a subnet mask of 255.255.224.0.
A /19 CIDR prefix indicates that the first 19 bits are dedicated to the network portion of the IPv4 address. This means 8 bits for the first octet, 8 for the second, and 3 for the third octet. The third octet's 3 network bits (11100000) translate to 128+64+32 = 224, making the mask 255.255.224.0.
255.255.240.0 corresponds to a /20 subnet mask (16 network bits + 4 network bits).
255.224.0.0 corresponds to an /11 subnet mask (8 network bits + 3 network bits).
255.240.0.0 corresponds to a /12 subnet mask (8 network bits + 4 network bits).
Concept tested: CIDR to subnet mask conversion
Topics
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