Which of the following IP addresses is most suitable for matching all IP packets in the subnet 10.1.128.0, mask 255.255.255.0?

Correct option is B

To match all IP packets within the subnet 10.1.128.0/24, the wildcard mask is 0.0.0.255. This means the last 8 bits are "don’t care" bits, allowing any value from 0 to 255 in the last octet while keeping the first three octets fixed.
Important Key Points:
1. Subnet Mask (255.255.255.0): Indicates that the first three octets (24 bits) are fixed, and the last octet is variable.
2. Wildcard Mask: Used in access control lists (ACLs) to specify the range of addresses. It’s the inverse of the subnet mask.
3. The subnet 10.1.128.0/24 includes addresses from 10.1.128.0 to 10.1.128.255.
Knowledge Booster:
· Subnet Range Calculation: The range is determined by keeping the fixed bits constant and varying the "don’t care" bits.
· Common Wildcard Masks:
· 0.0.0.0: Matches a specific address.
· 0.0.0.255: Matches all addresses in a /24 subnet.
· 0.0.255.255: Matches all addresses in a /16 subnet.
· Access Control Lists (ACLs): Widely used in routers and firewalls for controlling traffic based on IP addresses.