Can subnets be upgraded without impacting the entire network?

• A. No, upgrades require global network downtime.
• B. Yes, subnets can upgrade independently via their governance and VM update processes.
• C. Subnet upgrades must receive approval from all validators on the P-Chain.
• D. Subnet upgrades are not possible without a network-wide hard fork.

Answer: (B)

Subnets are designed to be modular pieces of the network, each with its own validator set and VM. Because of that separation, a subnet can adopt changes on its own timeline. The upgrade is driven by the subnet’s governance and a VM update process, where validators vote to move to a newer VM version. Once the subnet reaches consensus, it starts using the updated VM without requiring the entire network to coordinate or pause. This means you can bring new features, fixes, or improvements to a specific subnet without downtime or changes to other parts of the network. Global network upgrades or downtime would only be needed if you were attempting to upgrade the entire system at once, not for a subnet-specific upgrade.