listen EADDRNOTAVAIL 报错了怎么办？

events.js:160
      throw er; // Unhandled 'error' event      ^
Error: listen EADDRNOTAVAIL ip:9999
    at Object.exports._errnoException (util.js:1036:11)
    at exports._exceptionWithHostPort (util.js:1059:20)
    at Server._listen2 (net.js:1239:19)
    at listen (net.js:1288:10)
    at net.js:1398:9
    at GetAddrInfoReqWrap.asyncCallback [as callback](dns.js:62:16)
    at GetAddrInfoReqWrap.onlookup [as oncomplete](dns.js:81:10)