A2S (Source Engine) queries are used by game browsers to retrieve server info like player counts and map names. Cosmicguard’s A2S Caching answers these queries at the network edge, protecting your server from query floods and lag.
| Reading Time | Difficulty | Last Updated |
|---|
| 3 minutes | Intermediate | January 2026 |
Quick Navigation
| Section | What You’ll Learn |
|---|
| What is A2S Caching? | The technology behind edge-querying |
| Benefits for Owners | CPU savings and visibility |
| How to Enable | activating caching on your IP |
What is A2S Caching?
When a player refreshes their server list in Steam, their client sends an A2S_INFO packet. Normally, your game server has to process this. During a “Query Attack,” thousands of these packets can overwhelm your server CPU.
With A2S Caching:
- Cosmicguard’s firewall learns your server’s current status (Players, Map, Name).
- The firewall stores this info for a few seconds.
- When new queries arrive, the Firewall answers them directly.
- Your game server never even sees the traffic.
Benefits for Owners
- Zero CPU Lag: High player-count servers or those under query attacks stay perfectly responsive.
- Improved Visibility: Since the firewall answers instantly, your server will never show as “Timed Out” in game browsers.
- Customizable: The cache refreshes every few seconds to ensure your player count is always accurate.
How to Enable
A2S Caching is a feature exclusive to certain Cosmicguard Protection Profiles.
- Go to the IP Addresses tab.
- Ensure your IP is on the Cosmicguard network.
- Select a Valve-game profile (e.g., Rust, CS2, GMod).
- The A2S Caching logic is automatically integrated into these specialized profiles.
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Last Updated: January 2026 | Need Help? Contact our 24/7 support team!