All servers we track are queried periodically for server information and player statistics. We’ve built our own application that queries the servers and does additional things like attempting to filter out fake/redirect servers (still a WIP).
There are a few possible reasons why a server is showing offline in our list, but the server is online in reality.
How Do We Retrieve Server Info?
Before proceeding, let’s clarify how we retrieve information from servers we list and track.
As of right now, we primarily use A2S queries to retrieve server information (specifically A2S_INFO for general server info and A2S_PLAYER for player stats). We also use other methods if the A2S query cannot be used and in the future we will be adding more so we can support tracking servers in different games.
Query Program Adjustments
The query program is a pretty neat program, but, at least during the time of this writing, there are still a lot of adjustments that need to be made in terms of timeout settings, query interval delays, etc. So it is possible that our program isn’t tuned well enough for certain servers depending on the location, latency, network, and more.
A2S_PLAYER Query Requirement
One common thing we do for servers that have <= 255 players is require a response from the A2S_PLAYER query. If the server’s network provider drops these types of queries/packets, our system will determine the server is offline. I did add the option to exempt certain servers from this requirement. Therefore, you may reach out to me if you’d like a server to appear online in the server list without the player query being required. Just keep in mind that players won’t be tracked for these servers.