7 Configuration, Verification, and Troubleshooting Free Online FlashCards

What do Cisco IOS prompts reveal?

The prompt indicates the current mode: `>` is user EXEC, `#` is privileged EXEC, `(config)#` is global configuration, and `(config-if)#` is interface configuration.

How do running and startup configurations differ?

The running configuration is active; the startup configuration is the saved configuration used at boot. Compare them if a change disappears after a reboot.

What is the difference between `show ip interface brief` and `show interfaces`?

`show ip interface brief` gives a quick overview of interface addresses and status; `show interfaces` provides detailed counters and link information.

Why does a failed ping not prove that a destination is unreachable?

A failed ping is evidence, not a diagnosis: ICMP may be filtered, or a device may not answer it even when other traffic works.

What should you establish first when describing a network failure?

Start by establishing which devices, users, destinations, or applications are affected, when the failure began, and whether anything changed.

How does testing from near to far help troubleshoot connectivity?

Test progressively from the endpoint and local gateway through relevant routed hops to the destination. This helps locate the failure boundary.

What does `administratively down` usually indicate?

`administratively down` usually means the interface is disabled. Use `no shutdown` only if that interface should be active.

What should you check when a host cannot reach peers in its VLAN?

Check the host’s addressing and mask, access-port VLAN, MAC learning, and spanning-tree forwarding state.

What should you investigate if an IP works but its hostname does not?

Check DNS configuration and name resolution. Comparing a test by hostname with one by IP helps distinguish name-resolution failure from reachability failure.

When is `debug` appropriate, and how should it be used?

Use `debug` only when ordinary verification is insufficient and a specific event must be observed. Choose a narrow debug, monitor device load, collect output briefly, then stop it.

When should you save a configuration change?

Save only after verifying the intended change. Copying the running configuration to the startup configuration preserves it for boot.

How can you verify the route toward a destination?

Use `show ip route` to inspect the routing table and check for a matching destination prefix and the expected next hop or exit interface.