One cable, one office
An office has one internet line, one router (a device that links the office to the internet) and one power supply. A digger cuts the line outside. Forty people cannot work.
Nothing was wrong inside the building. One part failed and took everything with it. That kind of weak point has a name.
Key words
| Word | What it means |
|---|---|
| Single point of failure | One part whose failure stops the whole system. |
| Redundancy | Having a spare part so a failure does not stop the system. |
| System failure | When hardware, software or power stops working. |
| User account control | Managing what each account may do and removing accounts that should not exist. |
| Privilege | The power an account has to change things. |
| Shared account | One account used by several people, so nobody can say who did what. |
| Leaver | A person who has left the organisation. |
| Router | A device that sends data between networks. |
| Network | Computers and devices joined together so they can share data. |
The cells students fill in are left blank in this preview.
By the end of this lesson
Note
I can find single points of failure, say why systems fail, and explain why user accounts need control.
Starter: what you already know
Have a go
Starter: what you already know
3 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.
Cycle 1: single points of failure
Look at any system and ask: if this one part stops, does everything stop? If yes, it is a single point of failure.
Common ones: one router, one internet line, one power supply, one server, one key person who holds all the passwords.
The fix is redundancy: a second part ready to take over.
Single points and their fix
| Single point | What stops | Fix |
|---|---|---|
| One internet line | All online work | A second line from a different provider |
| One power supply | The device | A second power supply and a battery backup |
| One switch in the cabinet | Every device on it | A spare switch, ready to swap in |
| One administrator | Fixes, when they are away | A second trained person and shared notes |
The cells students fill in are left blank in this preview.
Check: find the single point
Have a go
Check: find the single point
4 questionsYour answers are marked here and are not kept. A college account keeps every student’s marks.