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Throttling for Amazon Route 53 API requests

Amazon Route 53 throttles API requests on a per-account basis to maintain service stability and ensure fair usage for all customers. Route 53 applies two independent limits:

A request can be throttled by either limit. When a request is throttled, Amazon Route 53 returns an HTTP 400 error (Bad request). The response header also includes a Code element with a value of Throttling and a Message element with a value of Rate exceeded.

How throttling is applied

Amazon Route 53 uses a token bucket algorithm. Each limit has a bucket that holds a maximum number of tokens. Each request (for the request rate limit) or each change (for the change throughput limit) removes tokens from the applicable bucket. The bucket refills at a fixed rate every second, up to its maximum capacity. If refill tokens arrive when the bucket is already full, Route 53 discards them.

Two values describe each bucket:

You can use refill tokens as they are added; you do not need to wait for the bucket to refill completely.

Request rate token bucket sizes and refill rates

Route 53 applies request rate throttling at two levels:

A request consumes a token from both buckets and is throttled if either bucket is empty. The following actions have different default request rate limits.

For the complete list of Amazon Route 53 API actions, see Actions in the Amazon Route 53 API Reference.

CreateHealthCheck requests

You can submit one CreateHealthCheck request every 2 seconds per AWS account. This corresponds to the refill rate of 0.5 requests per second shown in the preceding table.

Change throughput limiting

In addition to the request rate limit, the API actions that modify DNS data are subject to a change throughput limit. This limit uses a separate token bucket that depletes based on the number of DNS record changes a request makes, not the number of requests. Change throughput is limited per AWS account, not per API action. All of the following actions draw from one bucket, which has a maximum capacity of 1,500 changes (burst) and refills at 100 changes per second (sustained).

Changes are counted as follows:

All other Amazon Route 53 API actions consume no change throughput tokens and are limited only by the request rate.

Example: You can submit a single request containing 1,000 changes (a burst), which consumes 1,000 tokens. After the burst, the bucket refills at 100 tokens per second. If you continue submitting 100 changes per second, you can sustain that rate indefinitely. If you attempt to sustain 500 changes per second, the bucket depletes and subsequent requests are throttled until it refills.

Monitor API throttling

You can monitor your Amazon Route 53 API usage by watching for HTTP 400 responses in your application logs, or by tracking API usage through CloudWatch metrics. When you receive throttling errors, your requests are exceeding one of the limits described in the preceding sections.

Retries and exponential backoff

When you poll or retry an API request, we recommend using an exponential backoff algorithm to calculate the sleep interval between requests. Exponential backoff uses progressively longer waits between retries for consecutive error responses. Implement a maximum delay interval and a maximum number of retries, and consider adding jitter (randomized delay) to prevent successive collisions. For more information, see Timeouts, retries, and backoff with jitter in the AWS Builders' Library.

Each AWS SDK implements automatic retry logic, including an adaptive retry mode that adjusts the client-side request rate in response to throttling. For workloads that regularly approach these limits, consider enabling adaptive retries. For more information, see Retry behavior in the AWS SDKs and Tools Reference Guide.

Requesting a limit increase

You can request an increase to either the API request rate or the change throughput limit through AWS Support. To request an increase:

Best practices for API throttling

For broader Amazon Route 53 guidance, see Best practices for Amazon Route 53.