Work through in order.
ESTABLISH
What exactly fails When it started What changed Who and what is affected
NARROW IT
One device or all? Wired as well as wireless? One destination or everything? Constant or intermittent?
TEST UPWARD
Link connected or wireless associated? Does the device have an address, mask and gateway? Can it reach the gateway? Can it reach an external address by number? Can it resolve a name? Can it reach the specific service and port?
INTERPRET
- Fails at address: local assignment or link
- Fails at gateway: local configuration
- Fails beyond gateway: connection or router
Number works, name does not: DNS Name resolves, service does not: that service or a blocked port
THEN
Change one thing, test, record.
BEFORE ESCALATING
Write down what you ruled out.
WHAT TO PROVIDE
Exact errors, times, test results, and what changed.
