Basics and OSI Flashcards
What are layers 1-3 of the OSI model
Network
Data link
Physical
What are layers 4-7 of the OSI model
Application
Presentation
Session
Transport
Which OSI level does a hub and cabling fit into?
Physical
What level does a NIC and switch fit into?
Data link
Which OSI level has 2 sub categories and what are they?
Layer 2: Data Link
Link Local Control - How the nic communicates with the OS and the flow of data between them
Media Access Control - The construction and addressing of frames using a MAC address
How long is a MAC address in characters and bits?
12 chars, 48 bits
What are two alternate names for a MAC address?
MAC-48 and EUI-48 (Extended Unique identifier)
What parts of a frame are the “header”
Those with information on where the frame is going as well as the “type” (type of data in the frame)
What resides within the trailer of a frame?
The FCS/CRC
True or false the payload within a frame is the data?
Ye
What is a Unicast?
Sending data to just one system
What is the MAC broadcast address?
FF-FF-FF-FF-FF-FF
What is a network protocol
The rules and unique identifiers agreed upon by the computers in a network. Different network protocols won’t allow communication.
Transmission control protocol / internet protocol is an example of a…?
Protocol suite
True or false: Frames exist within packets?
False. Packets exist within frames.
Why does each router that receives your data strip away the frame and add their own?
To make sure the next router to receive the data is compatible with the frame type used.
True or false: Mac deals with device to device delivery, IP deals with the final destination subnet
True
What happens if a router doesn’t support a mac frame type sent to it?
Connection failure.
What is layer 4 and what are three things it does.
Transport. Break data into chunks, add ports and seq data.
What is a simplified TCP packet?
Ip to, ip from, to port, from port, seq no, ack no, data.
What is the difference between the structure of a TCP and UDP packet.
TCP uses seq and ack, UDP uses length and checksum.
What is layer 5 and what does it do?
Session. Manages the sessions on a computer (queuing them and arranging priority) and makes sure data is sent to the right computer.
What is the output from netstat -a an example of from the OSI table?
Session
What is layer 6 and what does it do
Presentation changes the incoming data into a format readable my your computer’s applications. This includes encryption.
What does the application layer do?
Your applications. Browsers, etc.
Where does (did) a hub send data?
To all the systems connected to the hub
What uniquely identifies every NIC?
Media access control address
What Windows utility do you use to find the MAC address for a system?
ipconfig /all
A MAC address is known as a(n) __________ address.
physical
A NIC sends data in discrete chunks called __________.
frames
What is found at the start of a MAC frame?
Receiving system
A frame ends with a special bit called the frame check sequence (FCS). What does the FCS do?
Verifies that the data arrived correctly
Free slot
.
Which layer of the OSI model controls the segmentation and reassembly of data?
Transport layer
Which layer of the OSI model keeps track of a system’s connections to send the right response to the right computer?
Session layer
