----TRACERT command in the network command under Windows

Now network in all directions, cable fiber base station satellite, as long as operators can charge the place, there is a network, covering all regions of the world. Completely changed the previous communication basically roar of the situation. So broad network world, more than 100 meters need to relay amplified signal network cable, even now the fiber cable distance is limited. The world is so big, there is no statistics, in the limited IPV4, the number of global routers, there is no answer.

When we visit a website, how many routers and routed IPs are passed from the current host to the destination host?

Windows has a network command that can help us complete, and that's the magic of tracert.

Tracert (Trace routing) is a route trace utility that is used to determine the path taken by an IP packet access target. The Tracert command uses the IP time-to-Live (TTL) field and the ICMP error message to determine the route from one host to another host on the network.

Command parameters

The tracert command is very useful for understanding including solving large networks, and it can explore the network topology in a large LAN, except for some routers that prohibit pings (general egress routers or firewalls).

The tracert command function is similar to ping, but it gets more information than the ping command, which displays all the paths that the packet takes, the IP of the node, and the time spent. This command is more suitable for large networks.

The Tracert sends a response packet with a TTL of 1, when the TTL on the packet is automatically reduced by 1 after the router receives the TTL, and once a server is 1, equals 0, the router should send the "ICMP Time Exceeded" message back to the source computer. The source computer determines the router and time it has reached based on the information received. The next time you send the packet again, increment the TTL by 1, continuing with the test until the target response or TTL reaches the maximum value to determine the route. The route is determined by checking the "ICMP timed out" message sent back by the intermediate router. Some routers discard TTL-expired packets without asking directly, which is not seen in the Tracert utility, and we display request information for request timeouts.

Case Introduction

1. Use the ping command to test the TTL initial value of the Www.baidu.com server setting to 54, such as:

2, we test the road to Www.baidu.com after 11 roads, such as. Combined with the results of the ping command, I learned that the small series in ping www.baidu.com time to get ttl=54. Again by knowing that after 11 roads have arrived at our client, 54+11=65, www.baidu.com set the TTL initial value to 65. The request timeout in the figure is for the router to handle the ping command, and the ping response is turned off, so we don't receive any feedback from him.

Case Summary

Through the case study we can specify the routing and routing addresses that are routed between the current host and the destination host.

----TRACERT command in the network command under Windows