Domain Name System aka DNS is used to match domain names to the IP addresses. DNS is provided over the intranet and internet servers with different port numbers.DNS can use both transmission protocols TCP and UDP. But general usage is over UDP protocol because of its simplicity and speed.

域名系统又名DNS，用于将域名与IP地址进行匹配。 DNS是通过具有不同端口号的Intranet和Internet服务器提供的。DNS可以同时使用TCP和UDP传输协议。 但是由于其简单性和速度，一般使用基于UDP协议。

One of the used DNS port is TCP Port 53. TCP provides stability over the DNS resolutions process. With TCP 53 there will be no data loss over network transmission which makes DNS transaction more stable. But this will create some overhead for the server and client because of the TCP behavior.

使用的DNS端口之一是TCP端口53。TCP在DNS解析过程中提供了稳定性。 使用TCP 53，将不会通过网络传输丢失任何数据，这将使DNS事务更加稳定。 但这会由于TCP行为而给服务器和客户端带来一些开销。

The most known and popular usage protocol of DNS is UDP 53. Most DNS servers use UDP 53 port which provides simplicity and less resource usage.

DNS的最广为人知的使用协议是UDP53。大多数DNS服务器使用UDP 53端口，可简化操作并减少资源使用。

DNSSEC provides secure DNS transactions which will secure a domain name to IP translation secure manner. DNSSEC can use both UDP and TCP 53 ports. But as DNSSEC packets are generally larger than 512 bytes and UDP can transmit a maximum 512 byte TCP protocol is used for DNSSEC. So DNSSEC uses TCP 53 port for communication.

DNSSEC提供安全的DNS事务，该事务将确保域名到IP转换的安全方式。 DNSSEC可以同时使用UDP和TCP 53端口。 但是由于DNSSEC数据包通常大于512字节，并且UDP可以传输的最大512字节TCP协议用于DNSSEC。 因此，DNSSEC使用TCP 53端口进行通信。

翻译自: https://www.poftut.com/what-is-dns-server-or-protocol-port-number/