How to Enable A2S Cache on an IP Address

A2S Cache speeds up game-server query responses and reduces server load by caching the results of Steam/Source “A2S” queries (A2S_INFO, A2S_PLAYER, A2S_RULES). These queries power the Steam and in-game server browsers (including Rust) and are what make your server appear with its name, map, and player count.

What is A2S?

• A2S is a UDP query protocol used by Steam/Source games and many others to fetch basic server info.
• Browsers (e.g., the Rust server list) request info from thousands of servers; as servers reply to A2S queries, they appear in the list. If replies are slow or dropped, the server appears late or not at all.

Why A2S Cache matters

• Faster appearance in the server list: Caching serves frequent info requests quickly, so your server responds sooner to the Rust browser’s A2S_INFO bursts, helping it show up faster and more consistently.
• Lower perceived latency in listings: Query responses come back quicker when cached (and can be delivered from optimized infrastructure), reducing round-trip time for the listing request path.
• More resilient against query-abuse: Valve has hardened the query protocol due to reflection/abuse risks; caching/proxy layers further dampen the impact of A2S floods.

In short: A2S Cache helps Rust and other Steam-query games answer server-browser pings faster and more reliably, while protecting the game process from unnecessary work.

Supported Games

• Counter-Strike 1.6
• Counter-Strike: Source
• Team Fortress 2
• Project Zomboid
• Valheim
• Rust
• Garry’s Mod
• Insurgency
• Arma 3
• DayZ
• 7 Days to Die
• ARK: Survival Evolved
• Conan Exiles
• Unturned

How to enable A2S Cache (Firewall Panel)

1. Log in to the Firewall Panel.
2. Go to My IP Addresses and select the target IP.
3. Click A2S Cache in the Actions.
4. Click Configure A2S Cache.
5. In Ports, enter your server’s query ports:

• • Single: 27015
  • Multiple: 27015,27016,27017
  • Range: 27020-27025

6. Click Apply Cache.

Tip: Use your query port(s), not gameplay ports. (Many Source/Rust servers use the 27015–27020 range for queries, confirm your game’s config.)

Notes & best practices

• A2S Cache affects query traffic only, not gameplay packets.
• If you change server name/map, allow a short time for the cache to refresh.
• For private/low-traffic servers, caching is optional but still reduces burst load.
• A2S caching/proxying solutions exist industry-wide for exactly these reasons: reducing DOS risk, speeding query replies, and cutting bandwidth/CPU.

Updated on: 27/09/2025