Study 8 Network Testing and Troubleshooting with 12 free online flashcards. Review key terms, definitions, and concepts with this interactive flashcard deck.
In what order should you troubleshoot a network problem?
Start at the physical connection and move toward the application: check cabling and link state, addressing and VLANs, the gateway and routed path, DNS, then the application’s port.
What is a useful sequence for testing network reachability?
Test the local interface, a nearby peer, the default gateway, a remote IP address, then a hostname or application. This helps narrow the fault to a segment or service.
Why change only one thing before retesting?
Make one controlled correction at a time, document it, and retest. This makes it easier to identify which change affected the problem and whether other services were disrupted.
What does a failed ping or silent traceroute hop prove?
A failed ping or silent traceroute hop is a clue, not proof of a fault. Firewalls may block probes, and routers may not reply while still forwarding traffic.
What can a Windows address beginning with `169.254` indicate?
A Windows address beginning with `169.254` commonly means the computer did not obtain an IPv4 address from DHCP. Check the link, VLAN, DHCP service, or relay.
How does traceroute reveal hops along a path?
Traceroute sends probes with increasing time-to-live values to reveal responding hops along a network path.
What should you check if a destination works by IP but not by name?
If a destination works by IP address but not by hostname, investigate DNS servers, suffixes, and records.
Why does a successful ping not prove an application will work?
Ping uses ICMP, while applications usually use TCP or UDP. Test the actual service port with an approved tool; successful ping alone does not prove that port is reachable.
What cable faults can a wiremap tester detect?
A wiremap or verification tester can find opens, shorts, crossed or reversed pairs, and some split-pair faults.
Why is a continuity test not enough to certify a cable?
A certification tester measures performance against the applicable cabling standard and limit. Continuity alone does not certify a cable.
How can VLAN configuration prevent communication on an active link?
A wrong access VLAN or a trunk that omits the required VLAN can prevent devices from communicating even when the link is up.
Why compare switch interface counters over time?
Compare interface counters over time to see whether errors, drops, or other faults are increasing; a single accumulated total may be misleading.