// create a new DNS message msg := new(dns.Msg) // set message ID msg.Id = dns.Id() // add question to message question := dns.Question{"example.com.", dns.TypeA, dns.ClassINET} msg.Question = []dns.Question{question} // send message to DNS server c := new(dns.Client) _, _, err := c.Exchange(msg, "8.8.8.8:53") if err != nil { if err == dns.ErrTruncated { // handle truncated response, send request using TCP } // handle other errors }
// listen on UDP port 53 server := &dns.Server{Addr: ":53", Net: "udp"} go server.ListenAndServe() // handle incoming messages for { msg := new(dns.Msg) // read message from connection conn, err := server.PacketConn() if err != nil { // handle error } _, err := conn.ReadFrom(msgBuf) if err != nil { // handle error } // process message if msg.IsTruncated() { // send response using TCP } }In this example, a DNS server is created listening on UDP port 53. Incoming messages are handled in a loop, checking for a truncated response using the IsTruncated() method. If the response is truncated, the server can then send the full response using TCP.