The whole category in one page.
THE THREE THINGS EVERY CONNECTION NEEDS
A link, an address, and an agreed protocol. Almost every problem is one of those.
DIAGNOSE UPWARD, ALWAYS
Link, address, gateway, external address by number, name resolution, then the service.
Testing an external address by number separates connectivity from DNS in a single step.
TEST ON A CABLE
Most "slow internet" is wireless. Testing over wireless measures the wireless.
UPLOAD IS THE FORGOTTEN MEASUREMENT
Calls, video, backups and anything hosted locally depend on it.
A saturated upload degrades calls while downloads look fine, and a backup running in working hours is the usual culprit.
WHAT PROPAGATION ACTUALLY IS
Caches expiring, not a spreading process. Lower TTLs in advance of a planned change.
Before changing nameservers, record every existing record and recreate them first — it affects mail as well as the website.
WHAT FAILS MORE OFTEN THAN ANYTHING TECHNICAL
Heat, power, and cabling. Swapping a cable is the cheapest diagnostic there is.
BEFORE BLAMING A CERTIFICATE, CHECK THE CLOCK
FOR INTERMITTENT FAULTS
Record every occurrence with times. Without a log they are dismissed, and patterns never emerge from memory.
THE QUESTION THAT SOLVES MOST PROBLEMS
What changed? Document changes and you can always answer it.
