For the last two decades, the networking industry has been warning about the exhaustion of IPv4 addresses and the imminent takeover of IPv6. Yet, here we are, and IPv4 is still the backbone of enterprise networks. The question arises: Is subnetting still a relevant skill?

The Cloud Demands Subnetting

If you are building infrastructure in AWS, Azure, or Google Cloud, the very first thing you do is create a Virtual Private Cloud (VPC) and divide it into subnets. Cloud providers charge a premium for public IP space, and strict isolation of resources requires meticulous private IP management.

You cannot deploy a secure database tier without placing it in an isolated, private subnet. Miscalculating your CIDR blocks in a cloud environment can lead to IP overlap when peering VPCs or connecting back to on-premise networks via VPN.

IoT and Edge Computing

The explosion of Internet of Things (IoT) devices in corporate environments (smart cameras, sensors, HVAC controllers) means networks are denser than ever. Security best practices dictate that IoT devices must be segregated from corporate laptops and servers. This segregation relies entirely on VLANs mapped to distinct subnets.

The Reality of IPv6

While mobile carriers and massive ISPs have heavily adopted IPv6 to solve carrier-grade NAT issues, internal enterprise LANs have been slow to migrate. The sheer cost and operational risk of re-architecting an internal network to IPv6 means IPv4 (and therefore subnetting) will remain a foundational skill for the foreseeable future.