# Header Value Base Cache

The **Header Value Base Cache** feature allows you to **explicitly allow or deny caching when a request contains a specific HTTP header value**.\
This provides precise control over caching behavior for **Dynamic Content Acceleration** resources where certain header values determine whether content should be cached.

{% hint style="info" %}
This feature is available **only for Dynamic CDN Resources**.
{% endhint %}

## How Header Value Base Cache Works

When **Header Value Base Cache** is enabled:

* Medianova CDN inspects incoming requests for the configured **Header** and **Value**.
* If the request matches the defined rule:
  * **Allow** — the response is eligible for caching.
  * **Deny** — the response bypasses the cache and is fetched from the origin.
* Requests that do not match the rule follow the default caching behavior.

This mechanism allows cache decisions to be enforced **conditionally**, rather than only by cache key variation.

## Configure Header Value Base Cache

You can configure this feature from the [**Medianova Control Panel**](https://cloud.medianova.com).

{% stepper %}
{% step %}
**Open the Caching Settings**

Log in to the **Medianova Control Panel**, navigate to **CDN → CDN Resources**, select a **Dynamic CDN Resource**, and open the **Caching** tab.

<figure><img src="/files/5pY3O5y2JduArD85Csdp" alt="" width="563"><figcaption></figcaption></figure>
{% endstep %}

{% step %}
**Enable Header Value Base Cache**

Set **Status** to **On**.
{% endstep %}

{% step %}
**Select the Rule Type**

Choose the behavior for matching requests:

* **Allow** — matching requests are cached
* **Deny** — matching requests bypass the cache
  {% endstep %}

{% step %}
**Define the Header Rule**

Enter the rule parameters:

* **Header** — Name of the HTTP request header
* **Value** — Header value to match
  {% endstep %}

{% step %}
**Apply the Configuration**

Select **Submit** to save and apply the changes.
{% endstep %}
{% endstepper %}

* Only **one header value-based rule** can be active at a time.
* Header matching is **exact**; both header name and value must match.
* This feature controls **cache eligibility**, not cache key variation.
* Can be combined with **Header Base Cache** and **Cookie Base Cache** for advanced caching strategies.
* Incorrect use of **Deny** may significantly reduce cache hit ratio.

## Common Use Cases

* Prevent caching when a request contains a debug or preview header
* Allow caching only when a specific feature-flag header is present
* Enforce cache bypass for internal or authenticated traffic
* Control caching behavior based on application-specific headers


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