VPC and Networking
20 questions about VPC, Subnets, Networking, and Security for exam preparation.
A company needs to create a VPC with support for 500 hosts distributed across public and private subnets. The architect must select a CIDR block that allows future growth without wasting IP addresses. Which CIDR block is most appropriate?
Category: Design Resilient Architectures
Explanation
Detailed breakdown of the correct answer
VPC CIDR Planning
A /22 CIDR block provides 1,024 IP addresses, where AWS reserves 5 addresses per subnet (first, last, router, DNS, and future allocation).
For 500 hosts with public and private subnets, /22 provides sufficient capacity with room for growth (approximately 50-100% more) without allocating excessive unnecessary addresses.
Therefore, the correct answer is: 10.0.0.0/22 (1,024 IP addresses).
The option that says: 10.0.0.0/16 is incorrect because it provides 65,536 IPs, a massive waste of address space for 500 hosts, complicating CIDR management in complex architectures.
The option that says: 10.0.0.0/23 is incorrect because with 512 IPs and AWS reservations (5 per subnet), it's too tight without room for growth or failover.
The option that says: 10.0.0.0/24 is incorrect because with only 256 IPs it's insufficient for 500 hosts, even in a single subnet.