6 Diagnosing Network Problems Free Online FlashCards

What should you establish before troubleshooting a network problem?

Define the symptom, determine which devices or services are affected, and note when it began and any recent changes.

What is the recommended order for network troubleshooting?

Troubleshoot from the device outward, checking the physical or Wi-Fi link, IP settings, local and gateway connectivity, DNS, then the route and application.

What does a lit Ethernet link indicator prove—and not prove?

It shows that a physical link exists, but does not prove the cable or connection is error-free.

How can you test whether weak Wi-Fi signal is contributing to a problem?

Move closer to the access point to test for weak signal. Distance, walls, interference, congestion, or roaming can cause weak or intermittent service.

Which IP settings does a device need for local and remote communication?

A device needs a valid IP address and subnet mask or prefix; it also needs a default gateway to communicate beyond its local network.

What does a Windows IPv4 address beginning with 169.254 commonly indicate?

On a Windows IPv4 adapter, an address beginning with 169.254 commonly means the device did not obtain a DHCP address.

Which Windows commands can renew a DHCP lease?

After correcting a connection or DHCP issue, `ipconfig /release` followed by `ipconfig /renew` can renew the device’s DHCP lease.

What can a ping test to the default gateway tell you?

A failed gateway ping can point to a local link, address, VLAN, or gateway problem. A successful ping does not prove that every service or the internet is reachable.

What does DNS do?

DNS translates host names, such as `example.com`, into IP addresses.

What does it suggest when a destination works by IP but fails by name?

If access by IP works but a name lookup fails, inspect the configured DNS server, its reachability, and the queried record.

How do `nslookup` and `ipconfig /flushdns` differ?

On Windows, `nslookup` queries the configured DNS server rather than relying on the client’s DNS cache. `ipconfig /flushdns` clears that local cache.

What does `tracert -d <destination>` show?

On Windows, `tracert -d <destination>` shows responding route hops without performing DNS lookups for each hop.