1.2 Select the components required to meet a given network specification.

As you can imagine, there are many aspects you will need to take into consideration when putting together a network, specially if dealing with a large corporate network. It’s simply not the same, configuring a network for a small office with 5 employees than configuring a network for a corporate branch with 5000 employees.
Some of the concepts we need to consider when designing a LAN are very straight forward like physical space, cabling, power source, static IP addressing, etc. and some are more complex like flexibility, expandability, security, routing protocol implementation, dynamic IP addressing, IP sub-netting, etc. Basically, the complexity of a network is directly proportional to the size of the network itself.
Luckily, we are getting ready for the CCNA, and its scope states; “…skills required to install, operate, and troubleshoot small to medium-size enterprise branch networks”, so let’s keep this in mind.

1.1 Purpose and functions of network devices: routers, switches, bridges and hubs.

We are going to start, slowly but surely, building a theoretical network in our minds. In order to do this, we are going to start from the beginning; recognizing all the components of a modern network as well as some not so modern devices. For now, it is going to be a basic description of each device’s function, but we will elaborate on each concept as we move forward. Let’s begin.

Broadcast and Collision Domains.

Terms you need to understand.

Broadcast: In this case, a Data-Link layer (Layer 2) message sent to ALL devices attached to the same network segment.

Collision: When more then one device transmit data at the same time on shared media, the packets collide, data becomes corrupted and after a random period of time, devices have to re-transmit the data.

Broadcast Domain: All devices that a Broadcast message reaches at the Data -Link layer within a network is called a Broadcast domain. A network can have more then one Broadcast domain and a Broadcast domain is delimited by devices that stop Broadcast messages.

Collision Domain: Anywhere within a network where a Collision can occur. The limits of a Collision domain are marked by those devices that break up Collision Domains.