A system’s application servers need to be patched.
The requirements for maintenance work are as follows:
– System downtime is not allowed.
– The application server in use must be in the sane patch status.
– System performance must be maintained during patching work.
– Testing after patching must be done before the application server is in use.
– If any trouble occurs, recover the previous version in ten minutes.
Which of the following methodologies should be selected?
A . Rolling update
B . Patching directly
C . Blue-green deployment
D . Three staging environments
Answer: D