Second Conditional for Hypothetical Scaling Scenarios

"If we had ten million users, the current database wouldn't cope" is the correct second conditional: past simple "had" in the if-clause (referring to an imagined present, not the actual past) with "would" plus bare infinitive in the main clause, appropriate since the company does not currently have ten million users and this is a hypothetical scenario. Option B mixes a present simple if-clause with "would", which is inconsistent (that pattern belongs to zero or mixed conditionals, not the standard second conditional). Option C uses "won't" instead of "wouldn't", breaking the required conditional pairing. Option D incorrectly uses "will have" in the if-clause, which conditional if-clauses avoid.

"If our cloud budget doubled, we would migrate to a multi-region setup" is correct: past simple "doubled" in the if-clause plus "would migrate" in the main clause forms a standard second conditional describing a hypothetical, currently untrue budget scenario. Option B uses present simple "doubles", which does not match the "would" in the main clause under the second conditional pattern. Option C uses "will migrate" instead of "would migrate", breaking the required pairing with a past-tense if-clause. Option D incorrectly uses "would double" inside the if-clause itself; conditional if-clauses do not normally contain "would".

"If the primary region were to go down, traffic would fail over automatically" is correct: the formal second conditional pattern "were to + infinitive" is preferred over "was to" in careful technical or formal writing, regardless of subject, paired correctly with "would" in the main clause. Option A uses the more informal "was to", less standard in formal technical documentation. Option C incorrectly switches to "will" in the main clause, breaking the required second conditional pairing. Option D incorrectly uses the continuous "were going down" instead of the required "were to go down" pattern for hypothetical future events.

"If I designed this system from scratch, I would use event sourcing instead of CRUD" is correct: past simple "designed" with "would use" expresses a present hypothetical, i.e., an imagined alternative to the existing system, not something that happened in the past. Option B uses present simple in the if-clause, which does not fit the "would" pairing of the second conditional. Option C uses past perfect "had designed", which shifts the meaning to a hypothetical about the past (third conditional) rather than a present hypothetical. Option D omits "would" entirely in the main clause, which is required for the second conditional.

"If traffic spikes next week, we'll add more replicas; if we suddenly had ten times the load, we would consider a full re-architecture" correctly pairs a realistic first conditional (present simple + will) for a plausible near-term event with a hypothetical second conditional (past simple + would) for a much less likely, extreme scenario. Option A reverses the modal pairings in both clauses, mismatching tense and modal in each. Option C uses present simple "have" in the second clause, which should be past simple "had" to match the hypothetical "would". Option D incorrectly uses past simple "spiked" in the first, realistic conditional, which should remain present simple.