Network system administration
Administration means the daily running of a network. The person who does it is the network administrator.
- Accounts: create, change and remove user names. Give each person only the access they need.
- Monitoring: watch traffic, speed and which devices are on. Tools show a green or red light for each device.
- Records: keep a list of devices, addresses and settings, and write a log of changes.
- Help desk: answer users when something does not work.
Network system maintenance
Maintenance means keeping the network working and fixing it when it does not.
- Preventive: update software, clean and check cables, replace old parts before they fail.
- Corrective: find a fault and repair it. First ask: is it one device, or many? Check the cable, then the device, then the settings.
- Redundancy: keep a spare path or spare device, so one failure does not stop everyone.
- Backups: save copies of settings, so a new device can be set up fast.
Network system security measures
Security protects the network from bad people and mistakes.
- Firewall: a gate that allows safe traffic and blocks unsafe traffic.
- Strong passwords and two-step login.
- Updates (patches) close known holes.
- Encryption: scrambles data so outsiders cannot read it (for example Wi-Fi with WPA2 or WPA3).
- Least privilege: each user gets only the rights they need.
- Antivirus and logs: catch bad files and keep a record to find what happened.
A simple fault-finding routine
1) Ask what is broken and for whom. 2) Check the lights and cables. 3) Test with another device. 4) Look at the log. 5) Fix one thing at a time. 6) Write down what you did.
Key formulas and definitions
- Availability = uptime / total time x 100%
- Downtime = total time - uptime
- Three daily jobs: Watch, Fix, Shield
- Least privilege = only the access a person needs
Worked examples
1. A network ran for 100 hours and was down for 2 hours. Find the availability.
Uptime = 100 - 2 = 98 hours. Availability = 98 / 100 x 100 = 98%.
2. One computer in a lab cannot reach the internet but all others can. Where do you look first?
Only one is affected, so the problem is local. Check its cable and port light first, then its settings.
3. Why should a student account not be able to install software on lab computers?
This is least privilege. A student could install a virus by mistake. Fewer rights mean fewer risks.
Common mistakes
- Thinking a network is done once the cables are laid. It needs daily care.
- Using one shared password for everyone. Give each person their own account.
- Skipping updates because they are boring. Old software has known holes.
- Having no spare or backup, so one broken cable stops the whole office.