Game Server Query Port Explained: What It Does and Which to Open
The query port is how server browsers ask your server for its name, map and player count. Default query ports for popular games and how to test one.
Updated Oct 7, 2026 · 5 min read
On this page
A query port is a separate port that a game server listens on to answer "who are you?" questions from server browsers, Steam, and tracking sites: its name, map, player count, ping and whether it has a password. Players do not connect through it, they connect through the game port. If the query port is closed or wrong, the server still runs and people can still join by IP, but it does not show up in the server list, or shows as offline. Open the query port alongside the game port, usually over UDP.
Game port vs query port
| Port | Purpose | If blocked |
|---|---|---|
| Game port | Actual gameplay traffic | Nobody can join |
| Query port | Answers server browser and Steam queries | Server missing from lists, joining by IP still works |
| RCON port | Remote admin commands | Admin tools cannot connect |
Some games use the same port for game and query traffic. Others use a separate one, often the game port plus one. A few modern games do not use a query port at all, because they list servers through their own online service instead of Steam's.
How a query works
Most Steam games use Valve's A2S query protocol. When a player opens the server browser:
- Steam's master server gives the browser a list of server addresses that registered with it.
- The browser sends a small UDP query packet (
A2S_INFO) to each server's query port. - The server replies with its name, map, players, max players and version.
- The browser measures the round trip as the ping it shows you.
If step 3 never happens, the browser hides the server or shows it with no information. That is why query port problems look like "my server is not on the list" while friends joining by direct IP have no trouble.
Default query ports for popular games
| Game | Game port | Query port |
|---|---|---|
| Counter-Strike 2, TF2, Garry's Mod (Source) | 27015 UDP | Same as game port |
| Valheim | 2456 UDP | 2457 UDP (game port plus one) |
| Rust | 28015 UDP | Set with server.queryport, commonly 28017 UDP |
| DayZ | 2302 UDP | steamQueryPort in serverDZ.cfg, commonly 27016 UDP |
| ARK: Survival Evolved | 7777 UDP | 27015 UDP (QueryPort) |
| ARK: Survival Ascended | 7777 UDP | None, servers are listed through Epic Online Services |
| 7 Days to Die | 26900 TCP and UDP | 26900 TCP for queries |
| Project Zomboid | 16261 UDP | 16262 UDP also used |
| Space Engineers | 27016 UDP | Same as game port |
| Enshrouded | 15637 UDP | Same port (queryPort in config) |
Ports can be changed in each game's config. If you change the game port, check whether the query port moves with it (Valheim's does) or needs changing separately (Rust's and DayZ's do).
Testing a query port
From another network, so you test what the internet sees:
- Steam's built in check: in the Steam client, open View, Game Servers, Favorites, and add your server with
IP:queryport. If Steam shows its name and players, the query works. - Command line with Python: the
python-a2spackage queries a server directly:
pip install python-a2s
python -c "import a2s; print(a2s.info(('203.0.113.10', 2457)))"
A reply with the server name means the query port is open and answering. A timeout means it is blocked, closed or wrong.
- Online server checkers on game tracking sites do the same thing from the outside.
Remember that many query ports are UDP only. A generic "open port checker" that only tests TCP will say the port is closed even when it works.
Why the query port is often the problem
- Only the game port was forwarded. Home routers and firewalls need the query port too. See how to port forward a game server.
- TCP instead of UDP. A TCP rule on a UDP port does nothing.
- The server answers on a different port than you think. Check the server log on startup: many games print the ports they bound.
- Two servers on one machine. Both try to use the same default query port and only one wins. Give each server its own game and query ports.
- Server bound to the wrong address. On machines with several network interfaces, the server may listen on an internal address. Set the bind or IP option to the public interface, or
0.0.0.0.
Our full checklist is in game server not showing in the server list.
Query floods and DDoS
Query ports are a popular target for floods, because each tiny query makes the server do some work and send a bigger reply. Attackers can use exposed query ports to amplify traffic. Hosting providers often protect them with filters that cache A2S replies. At home, you mainly need to know that a sudden lag spike with lots of small UDP packets hitting the query port may be an attack. See DDoS protection for game servers explained.
Query ports on a hosted server
On a GamezServers server your server gets its own address with its ports already open, and the query port is set up from the game's server template, so it appears in the browser without router work. DDoS protection is always on. Your address is shown in the panel the moment the server is live, which with instant hosting is about a minute after paying for most games. If you still cannot find your server in the list, support can help by email at support@gamezservers.com.
FAQ
What is a query port on a game server?
It is the port that answers server browser and Steam queries with the server's name, map and player count. Players connect through the game port, not the query port.
Do I need to open the query port?
Only if you want the server to appear in server lists. Without it, players can still join by direct IP.
Is the query port TCP or UDP?
For most Steam games it is UDP. 7 Days to Die is an exception that uses TCP for queries. Check your game's port list.
What is Valheim's query port?
The game port plus one. With the default game port 2456, the query port is 2457 UDP.
Want a server without the setup?
From75¢
Pick a game, pay, play. Live the moment checkout finishes.
Minecraft