A.Test major changes before deployment and defer minor changes until during deployment. 
B.Document and verify rollback procedures.
C.Ensure consistency of code versions across the network.
D.Progressively modify procedures and documentation during implementation.

A.work staff attributes， such as skills and communication
B.redundancy， to prevent single points of failure
C.processes， such as documentation， change control， and labs
D.appropriate technology， such as hardware and software
E.tools， such as those for monitoring and reporting