CV0-003 Question #175: Real Exam Question with Answer & Explanation

The correct answer is A. /8. Class A IP addresses (1.0.0.0 to 126.255.255.255) use a default subnet mask of 255.0.0.0, which equals a /8 prefix length in CIDR notation.

Operations

Question

A technician needs to configure a virtual NIC on a Class A IP address network. Which of the following is the default subnet mask for this network?

Options

A/8
B/16
C/24
D/28

Explanation

Class A IP addresses (1.0.0.0 to 126.255.255.255) use a default subnet mask of 255.0.0.0, which equals a /8 prefix length in CIDR notation.

Common mistakes.

B. /16 (255.255.0.0) is the default subnet mask for Class B networks, which span 128.0.0.0 to 191.255.255.255.
C. /24 (255.255.255.0) is the default subnet mask for Class C networks, which span 192.0.0.0 to 223.255.255.255.
D. /28 (255.255.255.240) is a custom subnet used for very small networks with 14 usable host addresses and is not a default classful mask.

Concept tested. Classful IP addressing and Class A default subnet mask

Reference. https://learn.microsoft.com/en-us/troubleshoot/windows-client/networking/default-subnet-mask-ip-address-classes

Topics

#Class A network#subnet mask#IP addressing#CIDR

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