readme

• run command

  python ./start.sh

• test

  ```python dig @127.0.0.1 -p 9999 baidu.com

  ; <<>> DiG 9.16.1-Ubuntu <<>> @127.0.0.1 -p 9999 baidu.com ; (1 server found) ;; global options: +cmd ;; Got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 339 ;; flags: qr rd ra; QUERY: 1, ANSWER: 2, AUTHORITY: 0, ADDITIONAL: 1

  ;; OPT PSEUDOSECTION: ; EDNS: version: 0, flags:; MBZ: 0x0005, udp: 4096 ; COOKIE: cf2958cf5b8f520740e4d5a8625d4a26824b1325aed43d79 (good) ;; QUESTION SECTION: ;baidu.com. IN A

  ;; ANSWER SECTION: baidu.com. 5 IN A 220.181.38.251 baidu.com. 5 IN A 220.181.38.148

  ;; Query time: 31 msec ;; SERVER: 127.0.0.1#9999(127.0.0.1) ;; WHEN: Mon Apr 18 19:23:18 CST 2022 ;; MSG SIZE rcvd: 98 ```