Advanced Options (Custom Payload)

If left empty, the system will automatically inject a standardized probe for known ports (DNS, NTP, SNMP, Source Engine, etc.).

Info Ping HTTP TCP UDP MTR DNS

A port is required for UDP checks.

Check UDP Port Availability: Global Connection Test from 50+ Locations

Enter a domain or IP address with a port (e.g., 8.8.8.8:53) to begin the global UDP check.

Examples: 8.8.8.8:53 time.nist.gov:123 1.1.1.1:5060

Commonly Used UDP Ports

A list of the most frequent destination ports encountered in modern UDP network monitoring.

Port	Service	Description
53	DNS	Domain Name System; resolves hostnames to IP addresses.
67	DHCP	DHCP Server; used for dynamic IP allocation.
123	NTP	Network Time Protocol; synchronizes system clocks.
161	SNMP	Simple Network Management Protocol; used for network monitoring.
500	ISAKMP	ISAKMP; used for setting up IPsec VPN tunnels.
3478	STUN	STUN; used for NAT traversal in VoIP and WebRTC.
5060	SIP	Session Initiation Protocol (SIP); used for VoIP signaling.
27015	Source Engine	Source Engine Query; used by game servers (CS:GO, TF2, Rust).

Global UDP Port Checker & Payload Injector

The Check-Host UDP port checker allows network administrators and developers to test the reachability of connectionless transport layer protocols. Unlike TCP, the User Datagram Protocol (UDP) does not establish a dedicated handshake. It simply transmits packets (datagrams) directly to the target, making it exceptionally fast but inherently unreliable. This tool verifies if your edge network is properly receiving and processing these stateless payloads across more than 50 geographic nodes.

Stateless Routing & Payload Injection

Because UDP lacks a formal acknowledgment mechanism (like a TCP SYN-ACK), a standard empty packet will typically yield no response from the server, even if the port is open. To definitively prove a UDP port is active, our engine automatically injects application-specific hexadecimal payloads—such as a standard DNS query for port 53, or an NTP version request for port 123—to force the target application to reply.

Firewall & DDoS Mitigation Testing

UDP is the primary vector for massive volumetric DDoS attacks (like NTP or DNS amplification). Consequently, modern cloud firewalls and ISP scrubbing centers often deploy aggressive UDP rate-limiting or outright protocol drops. Utilizing a globally distributed UDP test helps security engineers confirm that legitimate traffic is bypassing the firewall rules correctly without triggering false-positive DDoS mitigation filters.

Gaming, VoIP, and Streaming Analysis

Real-time applications such as multiplayer game servers (Source Engine, Unreal), VoIP communications (SIP/RTP), and live video streaming rely almost exclusively on UDP to minimize latency. Dropped UDP packets manifest as voice jitter or game lag. Our Live UDP Check allows you to continuously monitor a target over a 60-second window, plotting latency spikes and packet loss on a real-time chart to diagnose transient network instability.