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Checking Network Connectivity and Troubleshooting
You can use the ping and traceroute commands to test connectivity to remote devices, and
both of them can be used with many protocols, not just IP. But don’t forget that the show ip
route command is a good troubleshooting command for verifying your routing table and the
show interfaces command will show you the status of each interface.
Using the ping Command
You’ve seen many examples of pinging devices to test IP connectivity and name resolution
using the DNS server. To see all the different protocols that you can use with the Ping
program, type ping.
The ping output displays the minimum, average, and maximum times it takes for a ping
packet to find a specified system and return.
Using the traceroute Command
Traceroute (the traceroute command, or trace for short) shows the path a packet takes to
get to a remote device. It uses time to live (TTL) time-outs and ICMP error messages to outline
the path a packet takes through an internetwork to arrive at the remote host.
Trace (the trace command), which can be used from either user mode or privileged mode,
allows you to figure out which router in the path to an unreachable network host should be
examined more closely for the cause of the network’s failure.
To see the protocols that you can use with the traceroute command, type traceroute
The trace command shows the hop or hops that a packet traverses on its way to a remote
device.
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