UDP
User Datagram Protocol: a fast, connectionless protocol used for DNS, gaming, and streaming.
UDP (User Datagram Protocol) is the other main transport protocol alongside TCP. Unlike TCP, UDP does not establish a connection first: it just sends data and hopes it arrives. There is no handshake, no guaranteed delivery, and no ordering. This makes UDP faster and more efficient for use cases where speed matters more than reliability: DNS queries, online gaming, video streaming, VoIP calls, and VPN tunnels (WireGuard). The trade-off is that lost packets are not automatically retransmitted. UDP port scans are inherently ambiguous because no response could mean "open" or "filtered."
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- About DNS Checker
- Build a DNS Resolver from Scratch in Node.js
- Build a DNS Resolver from Scratch in PHP
- Build a DNS Resolver from Scratch in Python
- DKIM Record Checker
- DNS Amplification Attack Explained: How Open Resolvers Enable Massive DDoS
- DNS Checker Bot & Scanner Documentation
- DNS Hijacking Explained: How Attackers Take Control of Your Domain's Resolution
- DNS Lookups in PHP: dns_get_record, gethostbyname, and Beyond
- DNS Lookups in Python: Complete Guide with dnspython
- DNS Over HTTPS Abuse: How Encrypted DNS Creates Security Blind Spots
- DNS Queries in Node.js: dns.lookup vs dns.resolve Explained
- DNS Root Servers Explained: The 13 Servers That Run the Internet
- DNS Tunneling Attack: How Data Is Smuggled Through Port 53
- DNS Water Torture Attack: How Random Subdomain Floods Overwhelm Nameservers
- Free DNS & Network Tools
- Home
- How DNS Queries Work: A Developer's Guide to the DNS Protocol
- How to Report a DDoS Attack to Your ISP: Evidence, Templates, and Escalation Steps
- How to Report Brute Force SSH and RDP Attacks: Log Evidence and Abuse Report Templates
- How to Report IP Address Abuse: The Complete Guide to Filing Reports That Get Results
- How to Report Port Scanning and Network Reconnaissance to an ISP
- IPv6 Adoption: Which Countries and TLDs Are Leading the Transition?
- Network & Security Tools
- Phantom Domain Attack: How Unresponsive Domains Exhaust DNS Resolvers
- Port Scanner
- The Complete dig Command Guide: Every Flag and Option Explained
- The Shrinking Perimeter: Common Service Exposure Across IPv4
- Unix Time Now
- What Is an Open DNS Resolver? Why It's Dangerous and How to Fix It