# CDN configuration recommendations


To configure your CDN distributions for delivering Apple HLS and low-latency HLS (LL-HLS) streams with MediaPackage, we suggest using the following approach. Ensure that all your usual default parameters in the CDN distribution configuration are compatible with the delivery of HLS and LL-HLS streams with MediaPackage.

## Honor MediaPackage 'cache-control: max-age' values


MediaPackage defines time-to-live (TTL) values for objects either statically or dynamically, depending on the object type. The specific TTLs are listed below, and it's strongly recommended that you honor these values and avoid overriding them at the CDN configuration level.
+ Multivariant playlist (for both regular HLS and LL-HLS) - half the duration of the media segments
+ Media playlists (regular HLS) - half the duration of the media segments
+ Media playlists (LL-HLS) - 1 second
+ TS media segments and init segments - 1209600 seconds (14 days)
+ CMAF media segments and initialization segments - 1209600 seconds (14 days)

## Include specific query strings in your CDN cache key


We recommend that you include the following query strings in the CDN cache key. 
+ `aws.manifestfilter`: used to customize the manifest contents, as described in [Manifest filtering](manifest-filtering.md).
+ `aws.manifestsettings`: used to apply time-shifted settings to the manifest contents, as described in [Time-shifted viewing](time-shifted.md).
+ `_HLS_msn` and `_HLS_part`: used to support LL-HLS playback request logic, as described in the *HTTP Live Streaming Documentation* [Enabling Low-Latency HTTP Live Streaming (HLS)](https://developer.apple.com/documentation/http-live-streaming/enabling-low-latency-http-live-streaming-hls).

MediaPackage ignores all other query strings. Don't include them in the CDN forward requests.

## Response timeout


LL-HLS uses the Blocking Requests mechanism for both playlists and media parts, which is signaled through the `EXT-X-PRELOAD-HINT` tag. This mechanism puts the origin response on hold until the object is fully available. Consequently, the CDN should also wait for the origin response, and therefore, the response timeout value in your CDN distribution should be at least three times your parts duration.

## Forwarded HTTP headers


You may consider including the Origin header in your CDN forward requests to MediaPackage as the only potentially necessary HTTP request header. In doing so, MediaPackage will respond with an `access-control-allow-origin` header, using the value passed as the Origin header value. If the Origin header is not included in the forward requests, MediaPackage will respond with an `access-control-allow-origin: *` header. Choose the approach that best fits your CORS requirements.

## Forwarded cookies


MediaPackage doesn't consider any cookies that may be sent together with forward requests. Therefore, it's advisable to exclude cookies from CDN forward requests.