The physical layer of the OSI model deals with bit-pushing, not to be confused with physical controls.  Make sure you have a firm understanding of the difference between each, as this could be an exam question.  Types of cables include:

Unshielded twisted pair – the most commonly used network cables.  They are not protected outside of a thin outer covering and are susceptible to interference, crosstalk, noise, and eavesdropping (surveillance). 

Shielded twisted pair – same as UTP, but enclosed in a metallic shield.  

Coax – used for cable; consists of a single thick conductor wire surrounded by a protective grounding shield.  Not subject to EMI or RFI, but expensive and harder to bend.

Fiber optic – light pulses instead of electronic pulses.  Glass or plastic inside the cable. Not susceptible to the weaknesses of other cabling, however it is expensive and harder to implement.  The three types of cables are:

  • Single mode – fewer reflections from a smaller diameter core results in longer transmission distance.
  • Multimode – more reflections from a larger diameter core results in shorter transmission distances.
  • Plastic optical fiber – very short distance due to plastic core and large diameter of core. 

We don’t believe the exam will focus too much on the specific terms within topologies and architectures since that is mostly terminology that you needed to be familiar with from your prior network training/certs, but there are some terms that are present in other domains that you should be aware of:

Token – ring topologies use a continuously circulating token (a frame) that is filled/appended and emptied based on communications that occur within the topology.  The term “Token” will appear in Domain 3 as well, so pay attention to this term.  

Star – this term also appears in Domain 3 as the star principle.  A star topology refers to all nodes connecting to a single device, which is what most topologies consist of today.  

Collision – there are collisions in Domain 3 with hashing algorithms, and collisions in Domain 4 as follows:

  • Collision detection (CD): part of the carrier sense multiple access (CSMA) protocol, CD is associated with ethernet, and if a collision occurs it will wait a random interval before retransmitting.  
  • Collision avoidance (CA): CSMA-CA is associated with wireless, and actually prevents collisions through the use of request to send and clear to send signals processed by the access point.  

Internet in the context of layer 1 (bit pushing)

Digital subscriber line (DSL) – issues include a limit in the distance between customers and central telephone office, and the ability to be connected to the internet for a long time.  

Cable – the compatibility standard is data-over-cable service interface specifications (DOCSIS).  Some security is provided by cable ISPs in that the modem and the core/head exchange cryptographic keys when the modem is powered on, however:

  • In both cases of DSL or cable implementations, computers should have personal firewalls, are patched for security, and have unnecessary protocols disabled.

Broadband over Power Line – an emerging technology that pushes bits over power lines.

Cellular/mobile network – a radio network distributed over land “cells” or geographic areas.

  • Portable transciever – a mobile device, typically a cell phone.
  • Base station / cell site – a fixed location transceiver that uses differing radio frequencies from its immediate neighbors in order to reduce interference.
  • Code division multiple access (CDMA) – encoding calls with a unique key to ensure “multiple access” can be achieved.  The carrier is not required to accept any given phone on its network. This implementation uses network white lists to verify subscribers and the carrier must approve switching of phones.  
    • Note the similarity between terms:
      • code division multiple access (mobile/cell transmission method), and;
      • carrier sense multiple access (network transmission protocol)
  • Global System for Mobiles (GSM) – customer information is stored on a SIM card, carrier must accept GSM compliant phones.

A bound network is simply a network that’s connected by a physical media.

An unbound network is simply one that’s not connected by physical media.

Li-fi refers to unbound, or wireless, currently under development, that uses light to send data.

Acoustic waves uses sound, and unfortunately ISC2 only provided two sentences on these which is what I’ve what I’ve given you here.  

One thing that ISC2 didn’t mention, but you should be aware of, is that these LiFi and Acoustic Wave are not susceptible to radio frequency interference or disruptions.

A line driver is basically an internal signal amplifier. If you work with domain 4, you probably know that signals typically can’t travel more than half a meter before they start to attenuate, so the line driver in theory can boost that signal, so that it can travel up to 100 meters

The light emitting diode (LED) also acts as a line driver.

Amplifiers are for analogue signals.

Repeaters regenerate a digital signal and strip off the noise.

Multiplexers combine signals into one path for transmission.

Multiplexers are good for when there’s limited bandwidth.

They range from simple hubs to sophisticated dense-wave division multiplexers (DWDMs) which combine multiple optical signals on one strand of optical fiber.

Concentrators are multiplex connected devices that basically enable one signal to be transmitted on a network. A hub or a switch is a type of a concentrator.

Infiniband is a high-speed, switched fabric network technology, that’s used to provide connections between supercomputers. It’s different from Ethernet because of it’s more sophisticated flow control, and congestion management.  It prioritizes packets into virtual lanes and allows high-priority traffic to be queued first.  It has more predictable degradation of performance with load increases, as opposed to Ethernet. Currently it provides up to 600gb of bandwidth for certain computing environments.

In telecommunications, frequency-division multiplexing (FDM) is a technique by which the total bandwidth available in a communication medium is divided into a series of non-overlapping frequency bands, each of which is used to carry a separate signal. This allows a single transmission medium like a cable or optical fiber to be shared by various independent signals.

WiMAX is wireless broadband that can theoretically deliver more than 30Mbps, but is usually offered at 6Mbps and performs even less, making it significantly slower than hard-wired broadband. 5G and LTE replaced a lot of the effort that was put into developing WiMAX, but, it’s heavily used outside the U.S. and in the aviation industry where having a physical infrastructure is difficult, or cost-prohibitive.

Wetware is a new term that refers to  any policies or procedures that guide the behavior of employees by way of education and training.  It’s called “wet” because it’s basically whatever’s inside your skull.  It’s the brain’s coding as opposed to hardware or software coding.