TCP协议

DNS 传输协议主要使用 UDP，端口号为53，也可用TCP（端口号也是53）。

DNS over TCP is a communication protocol used for resolving domain names to IP addresses. Unlike DNS over UDP, which is commonly used for small queries and responses, DNS over TCP is employed for larger amounts of data, such as zone transfers or when the response data exceeds the size limit of UDP packets. It provides a more reliable transmission but can be slower due to its connectionoriented nature.