Corporate Network Count Calculator

About this interactive

A network engineer plans addresses network by network, so the first job is to count the networks. Two kinds make up a company network. A LAN is the layer 2 network of switches and end devices behind one router interface: however many switches are cabled together, it is one IP network. Routers work at layer 3 and separate networks, so every link between two routers is an IP network of its own. A company with a headquarters LAN and two branches, each branch router linked to the headquarters router, has three LANs and two links: five networks. The second job is sizing. Every network has a network address, its first address, and a broadcast address, its last, and neither can be given to a device. So a LAN with 50 devices that need an address, the router's own interface among them, needs at least 52 addresses; later, when you subnet, you round that up to a block size. Read the other way, a range of 32 addresses can give addresses to 30 devices. A link between two routers has exactly two interfaces, so it needs two usable addresses. Type every answer as a number in digits. Anything you miss shows the answer and how to count it. Seven of the sixteen questions are drawn each run.

What you'll learn

Count the IP networks in a company network: one for each LAN of switches and end devices, and one for each link between two routers
Work out how many addresses a network needs, or how many devices a range can address, allowing for its network and broadcast addresses

Aligned to

CompTIA Network+

1.7 Given a scenario, use appropriate IPv4 network addressing.

Cisco CCST Networking

4.4 Explain basic routing concepts

2.2 Identify IPv4 addresses and subnet formats

Cisco CCNA

1.6 Configure and verify IPv4 addressing and subnetting

Key terms

Local Area Network: A network that connects devices within a limited geographic area such as a home, office floor, or building, where all devices share the same broadcast domain and communicate at high speeds with low latency. A router defines the boundary of a LAN by separating it from other networks.
Layer 2: The Data Link layer of the OSI model, responsible for MAC addressing and frame delivery on a local network.
Layer 3: The Network layer of the OSI model, responsible for logical addressing and routing packets between networks.
Router: A network device that forwards data packets between networks based on IP addresses.
Network Address: The first address in an IP network range that identifies the network itself and cannot be assigned to a host. It is formed when all host bits are set to zero.
Broadcast Address: The last address in an IP subnet range, formed when all host bits are set to one, used to send a single packet to every device on that network simultaneously.
Usable Hosts: The number of valid host addresses within a subnet, calculated by subtracting two from the total host count to exclude the network and broadcast addresses.

Topics

Network Design Layer 2 Layer 3 Usable Hosts Interactive Calculation

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