资料来源 : pyDict

存活时间,(简称为'TTL',一个数据包在网络上可以存活的时间)

资料来源 : Free On-Line Dictionary of Computing

Time to Live
     
        (TTL) A field in the {Internet Protocol} header which
        indicates how many more {hop}s this packet should be allowed
        to make before being discarded or returned.
     
        (1994-12-12)