Network Types & Topologies
Key Takeaways
- A LAN (Local Area Network) covers a single building or campus, a WAN (Wide Area Network) spans large geographic areas, a MAN (Metropolitan Area Network) covers a city, and a PAN (Personal Area Network) covers a few meters.
- Star topology is the most common modern network layout where all devices connect to a central switch — if one device fails, others are unaffected, but if the switch fails, the entire network goes down.
- Mesh topology provides maximum redundancy — every device connects to every other device (full mesh) or most other devices (partial mesh), making it ideal for critical infrastructure.
- VLAN (Virtual LAN) technology logically segments a physical network into separate broadcast domains, improving security and performance without requiring separate physical hardware.
- Network Address Translation (NAT) allows private IP addresses on the internal network to access the internet through a single public IP address, conserving IPv4 addresses.
Last updated: March 2026
Network Types & Topologies
Network Classifications
| Type | Scope | Example |
|---|---|---|
| PAN (Personal Area Network) | Within a few meters | Bluetooth headphones to phone, smart watch |
| LAN (Local Area Network) | Building or campus | Office network, school network, home network |
| WLAN (Wireless LAN) | Building/campus (wireless) | Wi-Fi network in an office |
| MAN (Metropolitan Area Network) | City or metro area | City-wide government network, cable TV network |
| WAN (Wide Area Network) | Large geographic area (global) | The internet, corporate networks connecting multiple cities |
| SAN (Storage Area Network) | Data center storage | High-speed Fibre Channel network connecting servers to storage |
Network Topologies
Star Topology (Most Common)
- All devices connect to a central switch or hub
- If one device fails, the rest continue working
- If the central switch fails, the entire network goes down (single point of failure)
- Easy to add new devices (just connect to the switch)
- Easy to troubleshoot (isolate the affected connection)
Mesh Topology
- Full Mesh: Every device connects to every other device
- Partial Mesh: Devices connect to several (but not all) other devices
- Maximum redundancy — if one link fails, traffic routes around it
- Expensive to implement (many connections required)
- Used in: WAN backbone, critical infrastructure, wireless mesh networks
Bus Topology (Legacy)
- All devices share a single backbone cable
- A terminator is required at each end to prevent signal reflection
- If the backbone cable breaks, the entire network goes down
- Collision-prone and slow — replaced by star topology
Ring Topology (Legacy)
- Devices connected in a circular loop
- Data travels in one direction (or both in dual-ring)
- If one device or link fails, the ring breaks (unless dual-ring with failover)
- Used in legacy Token Ring and FDDI networks
Hybrid Topology
- Combination of two or more topology types
- Most real-world enterprise networks are hybrid (e.g., star-mesh)
VLANs (Virtual LANs)
A VLAN logically segments a single physical network into separate broadcast domains:
| Benefit | Description |
|---|---|
| Security | Isolate sensitive departments (finance, HR, IT) from general network |
| Performance | Reduce broadcast traffic by limiting broadcast domains |
| Flexibility | Group users logically regardless of physical location |
| Cost Savings | No need for separate physical switches per department |
Example VLAN Setup:
| VLAN ID | Name | Subnet | Devices |
|---|---|---|---|
| VLAN 10 | Management | 10.0.10.0/24 | IT staff, network equipment |
| VLAN 20 | Finance | 10.0.20.0/24 | Accounting, finance team |
| VLAN 30 | General | 10.0.30.0/24 | All other employees |
| VLAN 40 | Guest | 10.0.40.0/24 | Guest Wi-Fi devices |
Key Point: Devices on different VLANs cannot communicate without a router (inter-VLAN routing). This provides security isolation between network segments.
Network Service Concepts
DHCP Relay
- When the DHCP server is on a different subnet from the requesting client
- A DHCP relay agent (usually a router) forwards DHCP requests across subnets
- Without a relay, DHCP broadcasts would not reach the server
DNS Hierarchy
- Root Servers → TLD Servers (.com, .org, .net) → Authoritative Servers (domain-specific)
- Local DNS cache → Router DNS cache → ISP DNS → Root if needed
- Recursive query: Client asks resolver, resolver does all the work
- Iterative query: Client asks resolver, resolver refers client to next server
Test Your Knowledge
Which network type covers a single building or campus?
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D
Test Your Knowledge
In a star topology, what happens if the central switch fails?
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Test Your Knowledge
What technology allows a single physical switch to be logically divided into separate networks?
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D