The Bits and Bytes of Computer Networking 1 Flashcards
What is a protocol?
A defined set of standards that computers must follow in order to communicate properly.
What are the 5 levels of the TCP / IP Network Model? Starting from the bottom.
1 Physical Layer 2 Data Link Layer 3 Network Layer 4 Transport Layer 5 Application Layer
In the OSI model, what are the 3 layers that the application layer is split into? From the bottom.
5 Session Layer
6 Presentation Layer
7 Application Layer
What is the physical layer?
Layer 1, the physical devices that interconnect computers.
What is the data link layer?
Layer 2, responsible for defining a common way of interpreting the signals that are sent over the physical layer, so that network devices can communicate.
What is the network layer?
Layer 3, allows different networks to communicate with each other through routers.
What is the transport layer?
Layer 4, sorts out which client and server programs are supposed to get the received data.
What is the application layer?
Layer 7, the actual data being sent.
What address is used at layer 2?
MAC address.
What address is used at layer 3?
IP address.
What protocol is used at layer 3?
Internet Protocol (IP)
What 2 protocols are used at layer 4?
Transmission Control Protocol (TCP)
User Datagram Protocol (UDP)
What are the main differences between TCP and UDP?
TCP = slower but very reliable. UDP = fast but unreliable.
What are the two types of data transfer cable at the physical layer, and how is data sent across each type?
Twisted copper pairs - binary is communicated across the wires as voltage changes.
Fibre optic - binary is communicated across the glass fibres by beams of light.
What is Crosstalk?
On copper cables, when an electrical pulse on one wire is mistakenly detected on another wire, results in missing/ incorrect data.
What are 2 benefits and a disadvantage of fibre optic cables?
Faster and longer distance transfer.
Less risk of data loss.
Expensive and fragile.
What Layer does a hub operate on?
1 - Physical layer.
What is a common issue with hubs?
Collision domain - As they send the information to every device on the network, can result in the electrical pulses of the various data being sent interfering with each other. Devices have to wait until network is quiet, which results in slow communications.
Which Layer does a switch operate on, and what address does it use to send data?
2 - Data link layer, MAC address.
What kind of network do hubs and switches connect devices on?
A LAN.
What does a router do, and what addresses/ layer does it use?
Connects devices on different networks (eg home network to ISP), IP addresses, layer 3 - network layer.
What Protocol does a router use?
BGP Border Gateway Protocol.
What is modulation and line coding?
A way of varying the voltage of the charge moving across a cable. Line coding is when this is specifically used for computing, to communicate binary.
What is the difference between simplex and duplex communication, and give an example of each.
Duplex - information flows both ways on the cable, eg, phone call.
Simplex - information only goes one direction, eg, baby monitor.
What is Full Duplex vs half duplex?
Full - some pairs of wires are reserved for transmitting in each direction, communication from both ends can be simultaneous.
Half - only one device can communicate at a time.
What is the most common kind of cable plug?
RJ45.
