The security department just conducted a penetration test on the published virtual servers and all of the SSL virtual servers returned the result "Allowed changing to weak certificate standard" in…

The security department just conducted a penetration test on the published virtual servers and all of the SSL virtual servers returned the result "Allowed changing to weak certificate standard" in the report. The reason for this result could be that the network engineer who configured the virtual servers forgot to __________. (Choose the correct option to complete the sentence.)