Networking glossary
Every networking term you'll meet on a CCTV, Wi-Fi or IT install — explained in plain English, with links to the calculators that put each one to work.
Addressing
- IP address
- A unique number that identifies a device on a network. IPv4 looks like 192.168.1.10; IPv6 looks like 2001:db8::1. Cameras, NVRs, switches and APs all need one.
- IPv4 vs IPv6
- IPv4 uses 32-bit addresses (~4.3 billion possible). IPv6 uses 128-bit addresses, effectively unlimited. Most CCTV gear still defaults to IPv4 inside private networks.
- Public vs private IP
- Private IPs (10.x, 172.16-31.x, 192.168.x) only work inside your network. A public IP is what the internet sees, usually shared by NAT on your router.
- Static vs DHCP
- DHCP hands out IPs automatically — easy but they can change. Static IPs are manually fixed — recommended for cameras, NVRs and any device an app connects to by address.
- DNS
- Domain Name System — turns human names like nvr.local into IP addresses. Most installs run fine without it for camera traffic, but cloud services and updates depend on it.
- MAC address
- A 12-character hardware ID baked into every network port (e.g. 00:1A:2B:3C:4D:5E). Used by switches and DHCP to recognize specific devices regardless of IP.
Subnetting
- Subnet
- A logical slice of a larger network. Cameras might live on 192.168.10.0/24 while computers live on 192.168.1.0/24 — same building, isolated traffic. Subnet calculator →
- CIDR notation
- Shorthand like /24 that says how many bits identify the network. /24 = 256 addresses (254 usable). Smaller numbers mean bigger subnets.
- Subnet mask
- The long form of CIDR: 255.255.255.0 = /24. Tells a device which addresses are local vs which need to go through the gateway.
- Gateway
- The router IP that a device sends traffic to when the destination isn't on the local subnet. Usually .1 or .254 of the subnet.
- Broadcast address
- The last address in a subnet (e.g. 192.168.1.255 in a /24). Reserved for messages sent to every device on the subnet — you can't assign it to a camera.
Networks
- LAN
- Local Area Network — the wired and wireless network inside a single site. Cameras, NVR, APs and PCs in one building usually share a LAN.
- WAN
- Wide Area Network — anything outside your LAN. The link from your router to the internet is a WAN connection.
- VLAN
- A virtual LAN that lets one physical switch carry multiple isolated networks. Best practice for CCTV: put cameras on their own VLAN so they can't reach the office PCs.
- VPN
- Virtual Private Network — an encrypted tunnel between two networks (or a remote user and a network). Lets you view cameras from off-site without exposing them to the internet.
- VNet
- Virtual Network — the cloud equivalent of a VLAN, used in Azure/AWS/GCP. You'd see this if cameras stream into a cloud VMS.
- SDN
- Software-Defined Networking — switches and routers controlled by central software instead of per-device config. UniFi controllers and Meraki dashboards are familiar examples.
Hardware
- Switch (managed vs unmanaged)
- Connects multiple wired devices. Unmanaged just forwards traffic; managed switches support VLANs, PoE control and per-port stats — required for serious CCTV installs.
- Router
- Moves traffic between subnets and out to the internet. In small installs the router, switch and Wi-Fi often live in one box; on larger jobs they're separate.
- Access point (AP)
- A device that broadcasts Wi-Fi. Plugs into your switch via Ethernet (often PoE-powered) and lets phones, laptops and wireless cameras connect.
- PoE switch
- A switch that delivers power and data over the same Ethernet cable, so cameras and APs only need one wire. Watch the total wattage budget. PoE budget planner →
- NVR
- Network Video Recorder — the box that records IP camera footage to disk. Sized by camera count, resolution, frame rate and retention. Storage calculator →
- NIC
- Network Interface Card — the Ethernet (or Wi-Fi) adapter inside a device. Servers and NVRs sometimes have two for redundancy or separating camera and management traffic.
Wireless
- SSID
- The Wi-Fi network name. Many installs run separate SSIDs for staff, guest and IoT/cameras to keep traffic segmented.
- WPA2 / WPA3
- Wi-Fi encryption standards. WPA3 is newer and stronger; WPA2 is still fine and more universally supported by older cameras.
- 2.4 GHz vs 5 GHz vs 6 GHz
- 2.4 GHz: longer range, slower, crowded. 5 GHz: faster, shorter range. 6 GHz (Wi-Fi 6E/7): fastest, very short range, requires modern client devices.
- Mesh & roaming
- Multiple APs sharing one SSID. Clients hop seamlessly between them as they move — useful for site-wide coverage with handheld devices.
Protocols
- TCP vs UDP
- TCP guarantees delivery and order — used for control, web, file transfer. UDP is fire-and-forget — used for live video and voice where late packets are useless.
- HTTP / HTTPS
- How browsers and apps talk to web interfaces (camera config pages, NVR dashboards). HTTPS is encrypted — always use it on public networks.
- RTSP
- Real Time Streaming Protocol — the standard way to pull a live video stream from an IP camera. Most NVRs and VMS software speak it.
- ONVIF
- An industry standard so cameras and recorders from different brands can discover each other and exchange streams. Profile S = streaming, T = advanced video.
- SNMP
- Simple Network Management Protocol — lets network management tools poll switches and APs for port stats, uptime, errors.
- NTP
- Network Time Protocol — keeps cameras and NVRs in sync. Critical for evidence: timestamps that drift undermine footage credibility.
CCTV-specific
- Bitrate
- How much data a camera produces per second (Mbps). Drives both bandwidth and storage — a 4MP camera at 8 Mbps fills ~3.5 TB per month.
- Codec (H.264 / H.265)
- How video is compressed. H.265 (HEVC) roughly halves storage vs H.264 at the same quality — but not all NVRs support it.
- DORI
- Detect, Observe, Recognize, Identify — pixel-density thresholds (per EN 62676-4) that tell you whether a camera can identify a face at a given distance. FOV & DORI calculator →
- FOV
- Field of View — the horizontal angle a camera can see. Determined by the lens and sensor. Lens calculator →
- IR cut-off
- A small filter that swings out at night so the camera can use infrared illumination for low-light video.
Plan it visually
Drop cameras, switches and APs on a real satellite map. SightPlanr handles the math — you focus on the install.