NexusSec.In many offices the network lives in one person's head. That works until they are on leave during an outage, or leave the company. Documentation is not glamorous, but it is what makes an outage short and a handover painless.
Why it matters
- Outages. Knowing which cable, which port and which provider to call turns hours into minutes.
- People leaving. See what to do when your IT admin resigns; good documentation makes that list much shorter.
- Audits and questionnaires. Customers, insurers and auditors ask for asset lists and diagrams.
- Incidents. During a security incident you need to know quickly what is connected to what.
The essential list
- Network diagrams. One physical view showing sites, links, firewalls, switches and access points, and one logical view showing VLANs, subnets and how traffic flows between them.
- IP address plan. Each subnet and VLAN, what it is for, and which addresses are fixed.
- Device inventory. Model, serial number, location, firmware version and support or warranty end date for every firewall, switch, access point, server and recorder.
- Internet links. Provider, circuit ID, static IP addresses, support number and contract end date for each connection.
- Where credentials are held. Admin passwords belong in a password manager with a shared vault and an emergency access arrangement. The documentation says where they are, never what they are.
- Configuration backups. Recent backups of firewall, switch and Wi-Fi controller configurations, stored off the devices, with a note of what each firewall rule is for.
- Wi-Fi networks. Each network name, what it is for and which VLAN it uses.
- Backups and restore. What is backed up, where, how to restore it, and when a restore was last tested. See backups that survive ransomware.
- Vendors and renewals. Support contacts, contract numbers and renewal dates for licences, support contracts and warranties.
- Change log. What changed, when, by whom and why.
Keep a copy off the network
If the documentation lives only on the file server, it disappears in exactly the incidents where you need it most, such as ransomware or a failed server. Keep a copy somewhere separate, such as a separate cloud account or a printed copy of the essentials, and keep it up to date.
Keeping it current
- Give the documentation an owner.
- Update it as part of every change, not afterwards.
- Review it every quarter against what is actually installed.
- Keep it simple. A shared folder with clearly named files that people update beats a tool nobody opens.
If an IT provider manages your network
The documentation is still yours. Make sure the contract says the provider keeps it current and hands it over in full if the contract ends, and hold your own copy. Our network design work starts by mapping what you have and ends with full documentation of the network.
