What is a subnet in Avalanche?

• A. A decentralized exchange built on Avalanche.
• B. A subnet is a set of validators with a custom VM and security rules, used to tailor performance, governance, and security for particular use cases or assets.
• C. A set of replay protections for transactions.
• D. A cross-chain messaging protocol.

Answer: (B)

In Avalanche, a subnet is a specific group of validators that run together under a single set of security rules and a custom VM tailored to a particular use case or asset. This arrangement lets you shape performance, governance, and security by choosing who validates and what logic the blockchain can execute. The validators in the subnet secure the blockchains that run on that subnet, while the VM defines the rules and operations those blockchains follow, so you can deploy specialized blockchains with behavior matched to your needs. The platform’s P-Chain handles creating and managing subnets and assigning validators, enabling you to scale or customize security for different applications. A usual example is a permissioned subnet for a regulated asset with its own compliance logic, distinct from public DeFi on another subnet. The other options describe different features of Avalanche but don’t define what a subnet is.