Valid host check for /22: Given subnet 172.16.17.0/22, which of the following is a valid host address (with mask shown)?

Introduction / Context:
Verifying a valid host requires matching both the IP's range within the subnet and the correct subnet mask. /22 networks often confuse because the broadcast address ends with .255, yet some middle .255 values can still be hosts.

Given Data / Assumptions:

• Subnet: 172.16.17.0/22
• /22 mask = 255.255.252.0
• We must pick an IP/mask pair that is valid within this /22.

Concept / Approach:
A /22 spans 4 contiguous /24s. Determine the network range, then confirm the candidate address falls within it and isn’t the network or broadcast address.

Step-by-Step Solution:

Verification / Alternative check:
Check each option's mask and range: only option D pairs the correct /22 mask and an IP inside the range without being network/broadcast.

Why Other Options Are Wrong:

• A: Mask is /30 and not the specified /22.
• B: IP and mask point to a different network entirely.
• C: Mask /23 and IP 20.x fall outside 16–19 range for the /22 given.
• E: Mask /24; also 19.255 would be the /24 broadcast if /24 were used, but the mask is wrong.

Common Pitfalls:
Assuming any .255 is always a broadcast; it only is when it matches the subnet’s actual broadcast boundary.

Final Answer:
172.16.18.255 255.255.252.0