What is Keepalive?

Keepalive, in the context of computer networking, refers to a mechanism where connections are kept open, or are actively probed to ensure they are still active. This can be used to prevent connections from being dropped due to inactivity timeouts, which are common in firewalls, load balancers, and network devices. Keepalive mechanisms can be implemented at various layers of the network stack, such as TCP keepalive or application-level keepalive messages. They are frequently used to maintain long-lived connections between clients and servers, improving performance and responsiveness by avoiding the overhead of repeatedly establishing new connections.