Approaches for efficiently routing messages using a server pool are provided. In an embodiment, the system attempts to ensure high availability of servers by enabling clients to specify a domain name for the server pool even though the server pool comprises multiple servers, each having a distinct name. When a client initiates a session by using the server pool's domain name, the system may select an available server with a different name, and will route the request and subsequent messages during the session to the selected server. The system may select a server from the pool having the lowest load. The system may also indicate servers that subsequent messages in the session are to transit. Subsequent messages may then be routed to indicated servers to enable application services on the indicated servers to take actions based on the messages and the direction of the messages.