Amazon VPC Subnet
Does ZopNight manage Amazon VPC Subnet?
Subnets carry no charge themselves; what they determine is placement: which availability zone, which route table, and which resources share a network segment. ZopNight maps every subnet on its 6-hour discovery sweep and uses that placement data to attribute cost, group environments, and explain cross-AZ transfer charges.
Rules that fire on Amazon VPC Subnet
No active rule family targets Amazon VPC Subnet today. Rules that used to are retired, and retired rules publish no pages and fire no findings. Scheduling and permissions coverage are unaffected.
At a glance
| Field | Value |
|---|---|
| Scheduling notes | discovery and topology context only. |
A subnet is an address range within a VPC where instances and services are placed. Subnets carry no direct charge but define placement, availability-zone spread, and which resources share a network segment, which matters for attributing and reasoning about cost.
Placement is the product
AWS meters nothing for a subnet: not its existence, its size, or its address consumption. What a subnet does is decide things that other meters care about: the availability zone a resource lands in (and therefore whether traffic to its peers crosses AZ boundaries at per-GB rates), the route table it inherits (and therefore whether egress flows through a billed NAT gateway or a free internet gateway), and the blast radius it shares with neighbours.
The role subnets play in ZopNight
Subnets are discovered automatically on the 6-hour cycle and used as placement context, not cost items. That context does real work: cost attribution can group resources by subnet into environments, cross-AZ data transfer charges become explainable when the subnet map shows which chatty services live in different zones, and a NAT gateway’s spend can be traced to the private subnets routing through it. Nothing about a subnet is schedulable because nothing about it runs.
Network layouts that leak money one layer up
Subnet design errors bill through other resources. A private subnet in AZ-b routing through a NAT gateway in AZ-a pays cross-AZ transfer on every egress byte, silently. Services split across zones without a reason pay per-GB inter-AZ rates for their own internal chatter. And an abandoned subnet full of stopped-but-not-terminated instances marks an environment that was paused rather than cleaned up. The subnet is the free tombstone over billed EBS volumes.
Reading the subnet map
The VPC console’s Subnets view shows each subnet’s VPC, availability zone, CIDR, and available address count. Route table association is the detail worth checking per subnet: it answers whether the subnet is effectively public or private, and which NAT path its workloads pay for. An empty subnet costs nothing and deletes cleanly once nothing references it.