Correct Answer: A. It replaces the date header in the HTTP response with the Citrix ADC system time in a conventional date format.

Short Explanation with reference:

A rewrite action is a set of rules that defines how the Citrix ADC appliance modifies the requests and responses that it processes. A rewrite action can use different parameters, such as target, expression, and pattern, to specify what part of the message to modify and how to modify it. The target parameter specifies the part of the message that is modified, such as the header or the body. The expression parameter specifies the new value that replaces the target. The pattern parameter specifies a string or a regular expression that matches the part of the target that is replaced.

In this scenario, the administrator configured a rewrite action as follows:

add rewrite action sync_date replace http.res.date.sys.time

This rewrite action uses the replace parameter, which replaces the entire target with the expression. The target is http.res.date, which is the date header in the HTTP response. The expression is sys.time, which is a built-in function that returns the Citrix ADC system time in a conventional date format, such as “Wed, 06 Sep 2023 12:45:12 GMT”. Therefore, this rewrite action replaces the date header in the HTTP response with the Citrix ADC system time in a conventional date format. This can be useful for synchronizing the time between the server and the client, or for preventing caching issues.

Therefore, the correct way to interpret this rewrite action is A. It replaces the date header in the HTTP response with the Citrix ADC system time in a conventional date format.

Configuring rewrite actions | NetScaler : How to Configure Rewrite Action - Citrix Customer Support : How to Use Built-in Functions in Expressions - Citrix Customer Support