220-801 · Question #249
Which of the following describes a Class A IP address?
The correct answer is C. The first octet is between 1 and 128 with a subnet mask of 255.0.0.0. Class A IP addresses use the first octet range of 1-126 (approximated as 1-128 in this question) and have a default subnet mask of 255.0.0.0.
Question
Which of the following describes a Class A IP address?
Options
- AThe last octet is between 1 and 128 with a subnet mask of 255.0.0.0
- BThe first octet is between 1 and 128 with a subnet mask of 255.255.255.0
- CThe first octet is between 1 and 128 with a subnet mask of 255.0.0.0
- DThe last octet is between 1 and 128 with a subnet mask of 255.255.255.0
How the community answered
(50 responses)- B4% (2)
- C94% (47)
- D2% (1)
Why each option
Class A IP addresses use the first octet range of 1-126 (approximated as 1-128 in this question) and have a default subnet mask of 255.0.0.0.
IP address classification is determined by the first octet, not the last octet; referencing the last octet is incorrect for class identification.
A subnet mask of 255.255.255.0 defines Class C addressing, not Class A, and Class A identification is based on the first octet range.
Class A addresses are defined by having a first-octet value between 1 and 126 (the question approximates this as 1-128) and a default subnet mask of 255.0.0.0, which provides 8 network bits and 24 host bits. The class is identified by the leading bit of the first octet being 0.
Both identifiers in this choice are incorrect - Class A uses the first octet for identification and a 255.0.0.0 mask, not the last octet with a 255.255.255.0 mask.
Concept tested: IPv4 Class A address range and default subnet mask
Source: https://learn.microsoft.com/en-us/troubleshoot/windows-client/networking/tcpip-addressing-and-subnetting
Topics
Community Discussion
No community discussion yet for this question.