Manifest Caching

For VOD and Cold CDVR (complete recordings):

Player does the Caching of Manifest ( DASH/ HLS ) and Playlist files (HLS)
In case Player switches to Another App ( Ex: Netflix / Amazon) which is not using AAMP Player and exit back to VOD , then player will use cached Manifest for a faster tune .

For Linear / Hot CDVR

For DASH , Player will never Cache Manifest for Live Stream
For HLS , Player will cache Main Manifest file for Live Stream , but Playlist files are not Cached .

For TTL Cache , Player does 3 mins of DNS Cache timeout setting
When a player instance is created , player creates a Curl instances for download files . Now the Curl instance is configured to maintain the DNS cache for 3 mins ( If any url is attempted again on the same curl instance , it will reuse the Cached info )
After Tune Complete or when moved to next channel , Player does closure of all the curl instance it created , that means DNS timeout set with that instance is closed with that instance .
For new channel , a new player or if same player instance a new curl instance will be created.
So setting DNS Cache timeout will apply or benefit if same curl instance is used for download . But across channel changes , new curl instances are created .
In Conclusion : Player is not doing TTL caching across channel changes.