How does Bitrix caching work with memcached?

Question

1C-Bitrix

I do not understand the logic of work - I set the time to 86400, I set a unique ID. The cache is reset somehow randomly:
- Sometimes I refresh the page and with each update there are requests to the database, as if caching is disabled.
- Sometimes when updating, the data is taken from the cache, and after "2 minutes", the cache seems to be reset again.

Answer 1

- maybe the managed cache is being reset
- maybe the space for the memcache is running out