This section describes commands
that are useful in network troubleshooting.
Probably the most common is the PING command which sends an echo test message to
another machine. If we get an echo we know that everything from the Network
layer down is OK.
layer and down are OK
||Network layer and
down are not OK
Use PING [computerName] to do a normal echo
test. Use PING -a [IPaddress] to determine a computer's name or DNS name.
Usage: ping [-t] [-a] [-n
count] [-l size] [-f] [-i TTL] [-v TOS]
[-r count] [-s count] [[-j host-list] | [-k host-list]]
[-w timeout] target_name
-t Ping the specified host until stopped.
To see statistics and continue - type Control-Break;
To stop - type Control-C.
-a Resolve addresses to hostnames.
-n count Number of echo requests to send.
-l size Send buffer size.
-f Set Don't Fragment flag in packet.
-i TTL Time To Live.
-v TOS Type Of Service.
-r count Record route for count hops.
-s count Timestamp for count hops.
-j host-list Loose source route along host-list.
-k host-list Strict source route along host-list.
-w timeout Timeout in milliseconds to wait for each reply.
The following error messages are commonly
returned by Ping during troubleshooting:
|TTL Expired in Transit
||The number of required hops
exceeds the TTL Time to Live. Increase TTL by using the ping-i parameter.
Use the tracert command to see whether
misconfigured routers have caused a routing loop.
|Destination Host Unreachable
||No local or remote route does
exists for a destination host, either at the sending host or at a router.
Troubleshoot the local host or the router's routing table.
|Request Timed Out
Reply messages were not received within the designated timeout period. Use
the ping -w command to increase the timeout from the default four seconds.
|Ping request could not find
||The destination host name
cannot be resolved. Verify the name and the availability of DNS or WINS