A Lambda function calling a downstream database is overwhelming the database during traffic spikes. How can you cap the function's concurrent executions while leaving the rest of the account unaffected?
A.Reduce the function's memory allocation
Memory affects execution speed/cost, not the number of concurrent runs.
B.Set reserved concurrency on the function
Correct. Reserved concurrency caps and guarantees the function's concurrency.
C.Lower the function timeout
Timeout controls duration, not concurrency.
D.Move the function into a VPC
VPC placement affects networking, not the concurrency ceiling.
Why this answer
Reserved concurrency sets a maximum on simultaneous executions for a specific function — excess invocations are throttled (retried for async sources). It both protects the downstream resource and reserves capacity for this function.
Correct answer: B · Last reviewed 2026-10-26
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