Chapter 1: Network Models Flashcards
0What’s the 1st Layer of the OSI Model?
Physical Layer
Physical Layer Responsibility
Moving data between computers, no matter what it does.
Ways that physical layer moves data
Copper Cabling, Fiber Optics and Radio Waves
7 layers of the OSI Model
- Physical
- Data
- Network
- Transport
- Session
- Presentation
- Application
What is a NIC? What is its purpose?
Network Interface Card; it servers as the interface between the PC and the network.
What does “MAC” in MAC address stand for?
Media Access Control
Where are MAC addresses located
Inside special firmware that’s built into the ROM of the Network Interface Card.
How many bits are a MAC address
48
What notation are MAC addresses displayed in? Describe.
Hexadecimal; each character represents 4 bits, and 12 hex characters represent 4 bits.
What base does the hexadecimal numbering system use to represent numbers? What number range does this represent?
16; 0 - 15 in base 10 values.
How are hexadecimal bases represented?
Letter and number
If 0 - 9 are the first 10 characters in the hexadecimal system, what are the last five characters used?
A, B, C, D, E
What do the first six hex digits represent in a MAC address?
The number of the NIC manufacturer.
Who are the IEEE? What do they do?
Institute of Electrical and Electronics Engineers; provides a block of MAC addresses to NIC manufacturers.
What do the last six hex digits represent in a MAC address? What are these referred to as?
The manufacturers unique serial number; the Organizationally Unique Identifier (OUI).
Can anyone else use these MAC addresses?
No
What else are the last six digits in a MAC address referred to as?
The device ID
What’s another name for a MAC address?
Physical Address
What does MAC48 mean?
The MAC address is 48 bits, the first 24 define the OUI.
Unit of data specified by a protocol at each layer of the OSI 7 layer model.
Protocol Data Unit
Different frame types are used in
Different Networks
Why must all NIC’s on the same network use the same frame type?
So they can communicate with other NIC’s
What are the five things in a generic frame?
- Recipient’s MAC address
- Sender’s MAC address
- Type
- Data
- FCS
What is the “type” field in the generic frame?
what’s encapsulated in the frame.
What is the “data” field in the generic frame?
what’s encapsulated , followed by a special piece of checking information called “frame check sequence.”
What’s the Frame Check Sequence (FCS)?
A special piece of checking information that uses a type of binary math, that the receiving NI uses to verify that the data arrived intact.
What’s the binary math that FCS uses?
Cyclic redundancy check (CRC)
How many sections does a frame have? What are they?
3;
- Header
- Payload
- Trailer
What’s in the header of a frame?
MAC address and type
What’s in the payload of a frame?
Whatever’s encapsulated in the frame.
What’s in the trailer of a frame?
The Frame Check Sequence (FCS)
Which layer in the OSI model is the only layer that has sub layers?
Data Link
Why is the NIC at both Physical and Data Link Layers?
Physical - interface between network and pc
Data Link - sending and receiving
What’s the second layer of the OSI model?
Data Link Layer
Purpose of Data Link Layer
Nonde to node delivery of information; ensure error free data transmission of information.
What are the two aspects/jobs of NIC?
- Logical Link Control (LLC)
- Media Access Control (MAC)