Why is UDP used for DNS instead of TCP? Isn't TCP supposed

Domain Name System - Wikipedia DNS primarily uses the User Datagram Protocol (UDP) on port number 53 to serve requests. DNS queries consist of a single UDP request from the client followed by a single UDP reply from the server. When the length of the answer exceeds 512 bytes and both client and server support EDNS , larger UDP … Two simple filters for wireshark to analyze TCP and UDP DNS uses port 53 and uses UDP for the transport layer. To filter DNS traffic, the filter udp.port==53 is used. As can be seen in Figure E, four queries were made to DNS over the course of this Le DNS va t-il utiliser de plus en plus souvent TCP Le DNS utilise traditionnellement surtout UDP comme protocole de transport. TCP est parfaitement légal mais, en pratique, il a été cantonné aux transferts de zone et à quelques requêtes où la réponse était trop grosse pour passer en UDP. UDP vs TCP - Which One Is The Best? - BitTorrentVPN

Feb 28, 2013 · Consider the subsequent TCP SYN packet sent by your host. Does the destination IP address of the SYN packet correspond to any of the IP addresses provided in the DNS response message? The destination of the SYN packet is, the same address that was provided in the DNS response message as the type “A” address of the webpage.

TCP is the protocol for many popular applications and services, such as LDAP, MySQL, and RTMP. In NGINX Plus Release 9 and later, NGINX Plus can proxy and load balance UDP traffic. UDP (User Datagram Protocol) is the protocol for many popular non-transactional applications, such as DNS, syslog, and RADIUS. TCP is comparatively slower than UDP. UDP is faster, simpler and more efficient than TCP. Retransmission of lost packets is possible in TCP, but not in UDP. There is no retransmission of lost packets in User Datagram Protocol (UDP). TCP has a (20-80) bytes variable length header. UDP has a 8 bytes fixed length header. TCP is heavy-weight.

Apr 13, 2016 · UDP or User Datagram Protocol is a connectionless protocol found in the transport layer of TCP/IP Model. It neither establishes a connection nor checks whether the destination computer is ready to receive or not; it just sends the data directly.

UDP – blksthl A part of the DNS service is that it uses UDP, and Azure Firewall uses SNAT for address translation from every internal source, resulting in every UDP request from one IP to an external provider (,, etc.) will use one port out of the 65.000 available in the TCP protocol for that unique destination. DNS issue open port 53 udp - Cisco Community