Tracert: Determines the path taken to a destination by sending Internet Control Message Protocol (ICMP) Echo Request messages to the destination with incrementally increasing Time to Live (TTL) field values. The path displayed is the list of near-side router interfaces of the routers in the path between a source host and a destination. The near-side interface is the interface of the router that is closest to the sending host in the path. Used without parameters, tracert displays help.
This diagnostic tool determines the path taken to a destination by sending ICMP Echo Request messages with varying Time to Live (TTL) values to the destination. Each router along the path is required to decrement the TTL in an IP packet by at least 1 before forwarding it. Effectively, the TTL is a maximum link counter. When the TTL on a packet reaches 0, the router is expected to return an ICMP Time Exceeded message to the source computer. Tracert determines the path by sending the first Echo Request message with a TTL of 1 and incrementing the TTL by 1 on each subsequent transmission until the target responds or the maximum number of hops is reached. The maximum number of hops is 30 by default and can be specified using the -h parameter. The path is determined by examining the ICMP Time Exceeded messages returned by intermediate routers and the Echo Reply message returned by the destination. However, some routers do not return Time Exceeded messages for packets with expired TTL values and are invisible to the tracert command. In this case, a row of asterisks (*) is displayed for that hop.
Examples:
To trace the path to the host named corp7.microsoft.com, type:
· tracert corp7.microsoft.com
To trace the path to the host named corp7.microsoft.com and prevent the resolution of each IP address to its name, type:
· tracert -d corp7.microsoft.com
To trace the path to the host named corp7.microsoft.com and use the loose source route 10.12.0.1-10.29.3.1-10.1.44.1, type:
· tracert -j 10.12.0.1 10.29.3.1 10.1.44.1 corp7.microsoft.com
| Syntax tracert [-d] [-h MaximumHops] [-j HostList] [-w Timeout] [TargetName] Parameters -d Prevents tracert from attempting to resolve the IP addresses of intermediate routers to their names. This can speed up the display of tracert results. -h MaximumHops Specifies the maximum number of hops in the path to search for the target (destination). The default is 30 hops. -j HostList Specifies that Echo Request messages use the Loose Source Route option in the IP header with the set of intermediate destinations specified in HostList. With loose source routing, successive intermediate destinations can be separated by one or multiple routers. The maximum number of addresses or names in the host list is 9. The HostList is a series of IP addresses (in dotted decimal notation) separated by spaces. -w Timeout Specifies the amount of time in milliseconds to wait for the ICMP Time Exceeded or Echo Reply message corresponding to a given Echo Request message to be received. If not received within the time-out, an asterisk (*) is displayed. The default time-out is 4000 (4 seconds). |
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