I am new to python using ldclient library to get value from LaunchDarkly in backend server. Does it get cache on backend server or there is network call on every reference?
I had assumption it would be getting cached with some TTL + any LD flag changes would do push the changes or restart the connection
Yes it is as you assumed. The SDK downloads all feature flags on initialization. Through a websocket connection, flag changes are automatically "streamed" into the SDK running in your application process.
You would typically not restart your application on flag changes.