AWS - VPC Fundamentals
Which CIDR block is valid for creating a subnet with exactly 128 IP addresses?
Which CIDR block is valid for creating a subnet with exactly 128 IP addresses?
easy📝 Conceptual Q2 of 15
Step-by-Step Solution
Solution:
Step 1: Calculate IP count for each CIDR
/25 means 32 - 25 = 7 bits for hosts, so 2^7 = 128 IPs.Step 2: Match the exact IP count
/26 gives 64 IPs, /24 gives 256 IPs, /27 gives 32 IPs. Only /25 matches 128 IPs.Final Answer:
10.0.0.0/25 -> Option AQuick Check:
/25 = 128 IPs [OK]
Quick Trick: 2^(32 - mask) = IP count [OK]
Common Mistakes:
MISTAKES- Mixing up /25 and /26
- Assuming /24 is always 128 IPs
- Not calculating 2^(32-mask)
Master "VPC Fundamentals" in AWS
Want More Practice?
15+ quiz questions · All difficulty levels · Free
Free Signup - Practice All QuestionsMore AWS Quizzes