Recording what exists.
WHY IT MATTERS
Servers outlive memory, and the person who set it up is not always available.
WHAT TO RECORD PER SERVER
What it is for Its addresses and hostnames What services run on it Where configuration lives What is scheduled Where backups go How to reach the console Who has access
WHY CONSOLE ACCESS SPECIFICALLY
It is needed precisely when you cannot reach the machine to look it up.
WHERE TO KEEP IT
Somewhere reachable when the server is not.
WHAT TO NEVER KEEP ONLY ON THE SERVER
Its own documentation.
WHAT TO RECORD ABOUT CHANGES
What was changed, when, and why.
WHY THE REASON
It is the part nobody remembers, and it determines whether the change can be safely undone.
WHAT TO KEEP IN VERSION CONTROL
Configuration files Scripts The documentation itself
WHAT A RUNBOOK SHOULD CONTAIN
The steps for a routine task, exactly.
WHAT TASKS DESERVE ONE
Restoring a backup Adding a site Renewing a certificate manually Recovering from a full disk
WHAT TO TEST
That someone else can follow it.
WHAT TO UPDATE
The document, when the procedure changes.
