UDP monitoring for services that don’t shake hands
DNS servers, VoIP gateways, WireGuard VPNs and game servers speak UDP. There’s no connection to open, so a TCP check can’t tell you if they work. A UDP monitor sends a packet and waits for the answer.
Example check · demo data
UDP monitoring checks a service that uses the connectionless User Datagram Protocol by sending a datagram to its port and confirming a valid response arrives within a timeout.
Why UDP needs its own kind of check
TCP starts every conversation with a handshake, so “did the connection open?” is a reliable health check. UDP doesn’t have one. You send a packet and either get a reply or you don’t, and “no reply” can mean the service is down, the packet was dropped, or the service simply doesn’t answer unsolicited packets.
That’s why UDP monitoring works best against services that reply to a request: DNS answers queries, NTP answers time requests, many game servers answer status queries.
Services people monitor over UDP
| Port | Service | What a reply proves | 53 | 123 | 161 | 500 / 4500 | 51820 | 5060 | 27015 and others |
|---|---|---|---|---|---|---|---|---|---|
| DNS | The resolver or authoritative server is answering | ||||||||
| NTP | Time sync is available to your fleet | ||||||||
| SNMP | The device’s management agent is up (see network monitoring) | ||||||||
| IPsec VPN | The VPN endpoint is reachable | ||||||||
| WireGuard | Only if the server is configured to respond confirm behaviour | ||||||||
| SIP / VoIP | Phone systems can register calls | ||||||||
| Game servers | Players can find and join the server |
How StatusEagle runs a UDP check
Confirm whether custom request payloads and expected-response matching are supported, and document them here.
Verification matters more for UDP than for anything else. A single dropped datagram is normal. Paging someone for it isn’t.
Limits worth knowing
Related monitoring
Pair these monitoring checks to ensure complete stack coverage.
Frequently asked questions
Still deciding? Start monitoring free and verify your first service in ~2 minutes.
UDP monitoring checks that a service using UDP, such as DNS or VoIP, responds to a datagram sent to its port within a set time.
Your first monitor takes about two minutes.
Free plan: 10 monitors, 3 locations, 1 status page. No credit card.