Which CIDR notation is the equivalent of the subnet mask of 255.255.192.0?

The correct answer is B. /18. To find the CIDR notation for the subnet mask 255.255.192.0, count the number of consecutive '1' bits in its binary representation.

Routing Fundamentals

Question

Options

A/19
B/18
C/20
D/17

How the community answered

(49 responses)

A
4% (2)
B
86% (42)
C
2% (1)
D
8% (4)

Why each option

To find the CIDR notation for the subnet mask 255.255.192.0, count the number of consecutive '1' bits in its binary representation.

A/19

A /19 subnet mask would be 255.255.224.0 (8+8+3=19 bits).

B/18Correct

The subnet mask 255.255.192.0 converts to binary as 11111111.11111111.11000000.00000000. Counting the consecutive '1' bits from left to right yields 8 + 8 + 2 = 18, thus the CIDR notation is /18.

C/20

A /20 subnet mask would be 255.255.240.0 (8+8+4=20 bits).

D/17

A /17 subnet mask would be 255.255.128.0 (8+8+1=17 bits).

Concept tested: CIDR notation and subnet mask conversion

Source: https://www.cisco.com/c/en/us/support/docs/ip/ip-version-4-ipv4/13793-27.html

Topics

#subnet mask#CIDR#IPv4 addressing

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