MongoDB 3.4 introduces features designed to support mission-critical applications, including document validation for data governance and the enhanced replication protocol, which delivers faster service recovery in the event of a primary failure, as well as stricter durability guarantees. The enhanced replication protocol reduces failover time by optimizing algorithms used to detect replica set primary failures and elect a new primary, with an optional electionTimeoutMillis parameter allowing users to configure their systems for optimal failover behavior. Additionally, MongoDB 3.2 simplifies sharded cluster management by deploying config servers as a MongoDB replica set, improving metadata consistency and manageability, and increasing the number of replica set members that can span more than three data centers.