Retry-After Header

Table of Content

• Syntax
• Directives
• Examples
• Browser Compatibility
• How to modify Retry-After header

The Retry-After response HTTP header indicates the time that the client must wait before attempting another request to a specific server. It is primarily used in instances where overload or maintenance is underway. This guide to system communications aids in managing server load and statutory downtime, thereby enhancing overall system performance and reliability.

Syntax

The Retry-After header can be defined in two ways:

Retry-After: <http-date>
Retry-After: <delay-seconds>Copy

Directives

• <http-date>: This directive is specified in an HTTP-date format.
• <delay-seconds>: This directive uses a nonnegative integer, representing the delay time in seconds.

Examples

Example of Retry-After header with HTTP-date:

Retry-After: Wed, 21 Oct 2015 07:28:00 GMTCopy

Example of Retry-After header with delay seconds:

Retry-After: 120Copy

Both examples instruct the client to repeat the request after the specified time.

Browser Compatibility

How to modify Retry-After header

ModHeader is a Chrome extension that allows you to manipulate HTTP request headers. To modify the Retry-After header:

1. Install the ModHeader extension from Chrome Web Store.
2. Click on the ModHeader icon, then click on 'Add' to add a new header.
3. In the 'Name' field, type 'Retry-After'. In the 'Value' field, either input the number of seconds the client should wait before reattempting or input the http-date when the client may try again.
4. Refresh the page to apply the modified header.

Modifying Retry-After header with ModHeader can be very useful for testing the behavior of your web application in response to this header. This can help you ensure that your application handles the Retry-After header correctly, improving its reliability and robustness under various network conditions.