Week 1 - Introduction to Computer Networking Flashcards
Define what is a “protocol”?
A defined set of rules/standards that computers must follow in order to communicate properly
(rules of delivering a piece of mail through a delivery system)
What does computer networking generally refer to?
the full scope of how computers communicate with each other
Why are network protocols important? 2
- computers can hear and understand each other with the same protocols
- repeat messages not fully delivered
What are the 5 layers of Networking of the TCP/IP model? Top to bottom
- Application
- Transport
- Networking
- Data Link
- Physical
What is the Physical Layer?
The physical devices that interconnect computers
The delivery truck (of bits of data)
(cables, connection points, and protocols for how signals are sent)
What is the Data Link Layer also known as? What protocol is introduced? What does it specify? What type of data transfer does it focus on?
Network interface layer
introduces first protocols (ethernet, wifi) and is responsible for specifying physical layer attributes and focuses on getting data to nodes on the same network/link.
What is the Network Layer? What device does it use and how? What protocol?
Internet Layer
Gets data from one node to another in different networks using routers. Uses common Internet Protocol
What does the Transport layer do? What are common protocols in this layer? Which is the unreliable delivery? What protocol does it use to get around?
Sorts out which clients and server programs are meant to get data
Common is TCP to deliver data reliably, uses IP to get around. UDP is also common but no reliable delivery.
What is UDP?
User Datagram Protocol
Unreliable delivery of data, delivers it everywhere
How delivery truck finds your specific house
What is the Application Layer? What does its protocols allow you to do?
Applications, directly interact with this layer. The protocols allow you to browse the web or send/receive data.
The actual package you can touch (interact with)
Out of the Cat cables, which is limited in range transporting data across long distances at high speeds?
Cat 6
What is crosstalk?
when an electrical pulse is detected on another cable causing an error in the transmission of data
receiving end can’t understand data causing it to be re-sent
Which is better and why? Cat 5 or Cat 5e?
Cat 5e is better as Cat 5 is older and more susceptible to crosstalk. Cat 5e is more reliable and faster.
What are Cat cables made of? What do they do?
Twisted copper wires inside a plastic insulator that send binary signals as voltage changes in 1s and 0s
(receiving end = interprets voltages into data using line coding)
What is the benefit of fiber optic cables distance-wise?
Can transport data across long distances at higher speed without potential data loss
What are point-to-point connections?
a single device is at the end of each cable
not for multiple computers to connect
What is a Hub? What layer is it? Can it inspect contents?
a physical layer device that allows multiple computers to interconnect on a single network (LAN)
No cannot inspect data, all computers end up receiving the data (congestion)
What is a network switch? What layer is it?
it’s a data link layer device that is like a hub but is able to inspect contents of ethernet data being sent to it from a computer to determine which system is meant to receive that data
Explain what routers do? What layer are they? What do they use to help them network?
Network layer
They forward data between independent networks using IP data and internal tables
How is a core ISP router different?
a core ISP router is able to handle more traffic and more complex traffic decisions
backbone of the internet
How do routers share global data with each other? How does it work?
BGP - Border Gateway Protocol
Lets them know the optimal path to forward traffic
Google Maps GPS of the world’s networks
What is a node?
a device connected to the internet
What is a server?
serves data to clients (customers) requesting that data (asking for food)
What is a client?
requesting the data from the server (receiving food)
Can nodes be both a server and a client?
Yes, almost all nodes are both at some point most aren’t purely a server or client
Can individual computer programs on the same node be servers and clients to each other too?
Yes
like Active Server Directory
What do you call a node that is a server but also a client? Which of the two?
It depends on its primary reason
If it’s to serve data to client, it’s a server (like an email server, even though it’s a client of a DNS server)
What could also occasionally be a server in your house?
A desktop (fetches data from servers so user can do their work)
How many wires are in a standard Cat 6 cable? How many pairs?
8 wires, 4 pairs
What is full duplexing?
When data is able to flow in both directions simultaneously
What is half-duplex? What layer is it?
A half duplex connection allows communication in both directions, but only one side can communicate at a time.
Physical layer
What is simplex communication? on what medium? What layer is it?
1 way communication channel over a cable or radio signal
Physical layer
What is EMI and RFI?
Electromagnetic interference
Radio Frequency interference
What are FTP, STP, UTP cables?
FTP - foiled twisted pair
STP - shielded twisted pair
UTP - unshielded twisted pair
What is the least expensive type of Ethernet cable for home/business?
UTP unshielded twisted pair
Which two Ethernet cable types can exist together for extra protection against interference? Where is this most likely used?
STP and FTP
in industrial environments where EMI/RFI is much higher than normal (more expensive option)
Which Ethernet cable is more used for Network tasks?
CAT cables
Which Ethernet cables are used for computer/router connections to hubs and Ethernet switches
and which for server connections —> Ethernet switches?
Straight through cables