This section, method, or task contains steps that tell you how to modify the registry. However, serious problems might occur if you modify the registry incorrectly. Therefore, make sure that you follow these steps carefully. For added protection, back up the registry before you modify it. Then, you can restore the registry if a problem occurs. For more information about how to back up and restore the registry, click the following article number to view the article in the Microsoft Knowledge Base:
How to back up and restore the registry in Windows
The TRACERT (Trace Route) command is a route-tracing
utility used to determine the path that an IP packet has taken to reach a
can run this utitily by typing tracert
at the command prompt.
This article discusses the following topics:
- How the TRACERT command works
- Troubleshooting with TRACERT
- TRACERT syntax
How the TRACERT Command Works
The TRACERT diagnostic utility determines the route taken to a
destination by sending Internet Control Message Protocol (ICMP) echo packets
with varying IP Time-To-Live (TTL) values to the destination. Each router along
the path is required to decrement the TTL on a packet by at least 1 before
forwarding it, so the TTL is effectively a hop count. When the TTL on a packet
reaches 0, the router should send an ICMP Time Exceeded message back to the
TRACERT determines the route by sending the first
echo packet with a TTL of 1 and incrementing the TTL by 1 on each subsequent
transmission until the target responds or the maximum TTL is reached. The route
is determined by examining the ICMP Time Exceeded messages sent back by
intermediate routers. Note that some routers silently drop packets with expired
TTLs and are invisible to TRACERT.
TRACERT prints out an ordered
list of the routers in the path that returned the ICMP Time Exceeded message.
If the -d switch is used (telling TRACERT not to perform a DNS lookup on each
IP address), the IP address of the near- side interface of the routers is
In the following example, the packet must travel through
two routers (220.127.116.11 and 18.104.22.168) to get to host 22.214.171.124. In this
example, the default gateway is 126.96.36.199 and the IP address of the router on
the 188.8.131.52 network is at 184.108.40.206. C:\>tracert
Tracing route to 220.127.116.11 over a maximum of 30 hops
1 2 ms 3 ms 2 ms 18.104.22.168
2 75 ms 83 ms 88 ms 22.214.171.124
3 73 ms 79 ms 93 ms 126.96.36.199
Troubleshooting with TRACERT
The TRACERT command can be used to determine where a packet
stopped on the network. In the following example, the default gateway has
determined that there is not a valid path for the host on 188.8.131.52. There is
probably a router configuration problem or the 184.108.40.206 network does not
exist (a bad IP address). C:\>tracert 220.127.116.11
Tracing route to 18.104.22.168 over a maximum of 30 hops
1 22.214.171.124 reports: Destination net unreachable.
TRACERT is useful for troubleshooting large networks where
several paths can be taken to arrive at the same point, or where many
intermediate systems (routers or bridges) are involved.
There are several command-line switches that can be used with
TRACERT, but they are usually not needed for standard troubleshooting.
TRACERT syntax: tracert [-d] [-h maximum_hops]
[-j host-list] [-w timeout] target_name
Specifies to not resolve addresses to host names.
Specifies the maximum number of hops to search for target.
Specifies loose source route along the host-list.
Waits the number of milliseconds specified by timeout for each
Name or IP address of the target host.
You can use the
-j option to force the outgoing datagram to pass through a specific
router. To use the -j option in this manner, use the IP source route option. For example, if you type
find that the used path is as follows:
To find the path to router4 and back to the
computer, type tracert -j
to router4 and back to the computer is traced. In this example, the path is
typically the following: