David Bombal Ccna
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Repeaters
It amplifies the signal, dont understand it. It recceives the signal and retransmit it so it cancover longer distances.
Hubs
Layer 1 devices, they are dumb and dont understand what they receive, they just repeat. No intelligence here.
Switches
Is the same as a bridge, but these can learn mac addresses more quickly by using hardware. It allow us to connect many devices in a local area network, is not used for WAN. Layer 2 because they use etherner frames. Intelligence based on Mac Addresses.
Routers
They use IP addresses to route from one network to another. They are called layer 3 devices and are used to connect to WAN. Intelligence based on IP addreses.
Attenuation
Refers to the reduction in the strenght or intensity of a signal.
Multiport Repeater
It is essentially a repeater with multiple rj45 ports. For example: a hub is a multiport repeater.
bridge
Is an intermidiate device between a switch and a hub. they learned where devices were in the network by using software.
Firewall
They allow us to stop bad people getting in to our network.
WLC
Wireless LAN Controllers are used in Enterprise networks in order to centrally manage Wireless Access Points
IDS
Intrusion Detection System. Is like a dog it will warn you when there is an attacker or intruder. It does not stop the attacker it warns you that there is an attacker and then you can do something. They are not in the flow of traffic, they just get copies of the traffic to see if there is a problem.
IPS
Intrusion Prevention System, can alert you that there is a problem but also block the attack. The traffic goes through the IPS and when there is an attacker it blocks it.
RFC
Request for Comments. Is a way in wich people discuss protocols and agree in what a protocol should be used.
protocol
Is a way to communicate. The protocols define rules to communicate.
Bits
Data at layer 1. When data is sent at the physical layer. We are sending zeros and ones across the physical layer.In fiber optic a 1 will be represented by light and on copper it will be represented by electricity.
IP
Internet Protocol. Is a number that you allocate to a device, that allows it to comunicate using a protocol.
HTTPS
Is an encrypted version of HTTP
Frames
Data at layer 2. When we are sending data through an Ethernet switch, which is a so called layer device, we are sending frames.
Packets
Data at layer 3. A router will route packets from one interface to another.
segments
Data at layer 4.
application
Data from layer 5 to 7
Type field on ethernet.
It helps the upper layer to understand what protoocol will be used, for example ip version 4 or ip version 6.
Well known port number
This where a server service will listen
ephemeral or random port number
This what you will use when you initiate session to a well known port number
Port 21 (TCP)
Used by FTP (File Transfer Protocol)
Port 80 (TCP)
Used by HTTP (Hypertext Transfer Protocol)
Port 69 (UDP)
Used by TFTP (Trivial File Transfer Protocol)
Port 23 (TCP)
Used by Telnet
Port 22 (TCP)
Used by SSH (Secure Shell)
Port 443 (TCP)
Used by HTTPS
Binary
A way of representing information using only two options.
ipconfig
is a command line tool that will show me my IP address when using windows.
IPv4
Internet Protocol version 4. 1. Layer 3 or network layer protocol. 2. connectionless protocol. In other words there are no sessions formed when traffic is transformed. 3- Packets treated independently 4-May take different paths. 5-Best effort of packet delivery. 6- no data recovery features 7- no built in session 8- no retransmission
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