Passive Causative in Technical English

"Had the codebase audited" follows the passive causative pattern: have + object + past participle, meaning "we arranged for someone else to audit the codebase" — the emphasis is on the arrangement, not on who performed the action (though "by an external security firm" can still be added). Option A uses the base form "audit" instead of the past participle "audited", which is ungrammatical in this structure. Option C uses the "-ing" form, which would express something different (and is not the causative pattern). Option B ("had audited the codebase") is simply the past perfect active/passive tense, meaning "we ourselves had already audited it" — it does not express the causative meaning of arranging for someone else to do it.

"Get the SSL certificate renewed" follows the "get" causative pattern (an informal variant of "have"): get + object + past participle. Option B uses the base form "renew" instead of the past participle, which is ungrammatical. Option C reverses the required word order — the object must come before the past participle in this structure, not after. Option D incorrectly inserts "to" before "renew"; the passive causative never uses a to-infinitive after the object, only a past participle. Note that "get" causatives often imply more personal effort or urgency than "have" causatives, making "get" a natural choice here given the release deadline.

"We have the database backed up automatically every night" is the correct passive causative, emphasizing that the team has arranged/configured this automatic process to occur, rather than performing it manually. Option A is a simple passive sentence stating a fact about the database without expressing who arranged it or that it is a deliberate causative setup — grammatically correct, but it does not use the causative structure the question asks for. Option C incorrectly uses "has backed up" (active present perfect) with "the database" as subject, which would mean the database itself performed the backing up, which is nonsensical since databases do not perform actions on themselves. Option D uses the noun "backup" instead of the past participle "backed up", which is ungrammatical in this verb slot.

"Haven't had the load balancer reconfigured yet" correctly negates the passive causative in the present perfect: haven't (negative auxiliary) + had (causative verb, base form after "have/has/haven't") + object + past participle. Option A uses the base form "reconfigure" instead of "reconfigured", which breaks the required past-participle pattern. Option C mixes "didn't have" (correct negative causative in past simple) with "-ing" ("reconfiguring") and "yet" (which typically pairs with present perfect, not past simple), creating an inconsistent tense combination. Option B scrambles the word order, incorrectly duplicating "had" in the wrong position.

"Did you have the legacy module migrated" is correct: "did" (past-tense question auxiliary) + subject + "have" (base form, since "did" already carries the tense) + object + past participle ("migrated"). Option A uses the base form "migrate" instead of the past participle. Option B omits the required "did" auxiliary, producing an ungrammatical question structure (it would need to be "Have you had..." to work as a present perfect question). Option C incorrectly uses "had" instead of the base form "have" after "did" — once "did" establishes the past tense, the following verb must revert to its base form, so "had" is a doubled and incorrect past marker.