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ping 返回的TTL数值代表什么?

ping 返回的TTL数值代表什么?

 1 [root@standby ~]# dig @202.106.0.20 www.iqiyi.com 2  3 ; <<>> DiG 9.8.2rc1-RedHat-9.8.2-0.30.rc1.el6 <<>> @202.106.0.20 www.iqiyi.com 4 ; (1 server found) 5 ;; global options: +cmd 6 ;; Got answer: 7 ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 22053 8 ;; flags: qr rd ra; QUERY: 1, ANSWER: 7, AUTHORITY: 0, ADDITIONAL: 0 9 10 ;; QUESTION SECTION:11 ;www.iqiyi.com.            IN    A12 13 ;; ANSWER SECTION:14 www.iqiyi.com.        7    IN    CNAME    static.dns.iqiyi.com.15 static.dns.iqiyi.com.    6    IN    A    111.206.13.6516 static.dns.iqiyi.com.    6    IN    A    111.206.13.6317 static.dns.iqiyi.com.    6    IN    A    111.206.13.6118 static.dns.iqiyi.com.    6    IN    A    111.206.13.6419 static.dns.iqiyi.com.    6    IN    A    111.206.13.6220 static.dns.iqiyi.com.    6    IN    A    111.206.13.6621 22 ;; Query time: 6 msec23 ;; SERVER: 202.106.0.20#53(202.106.0.20)24 ;; WHEN: Thu Sep 15 17:25:09 201625 ;; MSG SIZE  rcvd: 152

 

查看一共经历几跳路由

 1 [root@standby ~]# traceroute www.iqiyi.com 2 traceroute to www.iqiyi.com (111.206.13.63), 30 hops max, 60 byte packets 3  1  localhost (192.168.1.1)  2.924 ms  2.662 ms  2.429 ms 4  2  * * * 5  3  61.148.174.189 (61.148.174.189)  3.744 ms  3.555 ms  7.079 ms 6  4  124.65.58.237 (124.65.58.237)  6.910 ms  6.263 ms  6.062 ms 7  5  61.51.115.106 (61.51.115.106)  5.852 ms  5.635 ms  5.420 ms 8  6  bt-211-046.bta.net.cn (202.106.211.46)  6.722 ms  8.319 ms  8.019 ms 9  7  111.206.13.63 (111.206.13.63)  7.183 ms  3.643 ms  6.609 ms10 [root@standby ~]#

 

查看返回的TTL

1 [root@standby ~]# ping www.iqiyi.com2 PING static.dns.iqiyi.com (111.206.13.63) 56(84) bytes of data.3 64 bytes from 111.206.13.63: icmp_seq=1 ttl=58 time=7.56 ms4 64 bytes from 111.206.13.63: icmp_seq=2 ttl=58 time=9.46 ms5 ^C6 --- static.dns.iqiyi.com ping statistics ---7 2 packets transmitted, 2 received, 0% packet loss, time 1957ms8 rtt min/avg/max/mdev = 7.569/8.516/9.464/0.951 ms9 [root@standby ~]#

 

64 - 6 = 58



已知经过6跳路由,那么我们尝试设置ttl为6进行试验:

1 [root@standby ~]# ping -c 3 -t 6 www.iqiyi.com2 PING static.dns.iqiyi.com (111.206.13.66) 56(84) bytes of data.3 From bt-211-046.bta.net.cn (202.106.211.46) icmp_seq=1 Time to live exceeded4 From bt-211-046.bta.net.cn (202.106.211.46) icmp_seq=2 Time to live exceeded5 From bt-211-046.bta.net.cn (202.106.211.46) icmp_seq=3 Time to live exceeded6 7 --- static.dns.iqiyi.com ping statistics ---8 3 packets transmitted, 0 received, +3 errors, 100% packet loss, time 2017ms

 

已知经过6跳路由,那么我们尝试设置ttl为7进行试验:

 1 [root@standby ~]# ping -c 3 -t 7 www.iqiyi.com 2 PING static.dns.iqiyi.com (111.206.13.65) 56(84) bytes of data. 3 64 bytes from 111.206.13.65: icmp_seq=1 ttl=58 time=6.25 ms 4 64 bytes from 111.206.13.65: icmp_seq=2 ttl=58 time=12.1 ms 5 64 bytes from 111.206.13.65: icmp_seq=3 ttl=58 time=5.23 ms 6  7 --- static.dns.iqiyi.com ping statistics --- 8 3 packets transmitted, 3 received, 0% packet loss, time 2008ms 9 rtt min/avg/max/mdev = 5.233/7.885/12.167/3.057 ms10 [root@standby ~]#

 

ping 返回的TTL数值代表什么?