X-WS-RateLimit-Limit

IONOS CDN applies per-IP rate limiting to incoming requests, and the X-WS-RateLimit-Limit unofficial response header reports which rate limit is configured for the routing rule that matched the request.

Table of Contents

Usage

IONOS CDN rate limiting controls how many requests clients behind a single IP address are allowed to send each second. Administrators choose a rate limit class for each CDN routing rule, covering the scheme, hostname, and path prefix, and the X-WS-RateLimit-Limit header reports the configured ceiling back to the client.

Each edge server and each routing rule keeps its own bucket for the per-IP counters. Buckets are not shared across routes or edge servers, so the same client may see a different remaining budget depending on which edge server answers and which routing rule matches.

The header appears alongside X-WS-RateLimit-Remaining, which shows how many requests remain before the limit is reached. Together, these two headers give API clients a clear view of their current consumption relative to the allowed maximum.

This header follows the same pattern as the widely adopted X-RateLimit-Limit, but with the WS- prefix scoping the header to the IONOS CDN platform.

Values

Numeric request ceiling

The value is a positive integer representing the maximum requests permitted per second, per client IP, per routing rule. IONOS documents the limit as configured per routing rule and applied per client IP on each edge server. Crawl data shows 1000 as the value across every observed host.

Example

A response from an IONOS CDN edge server shows the rate limit ceiling, the value observed across every host in crawl data. Clients behind the requesting IP address are permitted 1000 requests per second on the matched routing rule.

X-WS-RateLimit-Limit: 1000

In practice, both rate limit headers appear together so API clients receive a complete picture of their current standing.

X-WS-RateLimit-Limit: 1000
X-WS-RateLimit-Remaining: 993

See also

Last updated: August 17, 2026