when the client clear the cookies then server use url writing to identify client. when first time user send request to client(cookies disable by client) then server create connection to receive request and process it and create unique id(number) and that id append to the client url.

becoz next time(with in session time expired) that same client send another same request to server , then server create new connection to receive and process request before process it check that id, if that id is present in server that means that client already visited(2nd time sending request) than server does not create new session it will use or maintain previous session and give responce to client. this happen again and again till client sending request to server with in that session time. if session i expire. Then this all process will start newly.