Network Models Flashcards
What is the 7 layer OSI model?
Open Systems Interconnection, model is a conceptual framework that divides network communications functions into seven layers that explains how a network works.
What are the 7 layers of the OSI model?
PDNTSPA
- Physical
- Data Link
- Network
- Transport
- Session
- Presentation
- Application
What is the Physical layer of the OSI model?
1st layer, Cabling, network card, getting 1’s and 0’s from one machine to another.
What is the Data Link layer of the OSI model?
2nd Layer, Mac Addresses / for NICs and Switches
What is the Network layer of the OSI model?
3rd Layer, Logical addresses, TCP/IP and Routers, packets are created
What is the Transport layer of the OSI model?
4th Layer, assembles and disassembles data 1500 bytes maximum, sequencing, segments
What is the Session Layer of the OSI Model?
5th layer, makes the actual connection to the remote host or other computers, uses Port numbers
What is the Presentation Layer of the OSI Model?
6th layer, makes sure that the Data gets to the application, not really important anymore.
What is the Application Layer of the OSI Model?
7th Layer, API or Application Program Interface, smart application
How is Data transferred from one device to another?
Frames or Packets in chunks of 1’s and 0’s
What is the cornerstone of Networking?
Packetized Data
Frames are created and destroyed in what hardware device?
Network Card (NIC)
Each hexadecimal character has?
4 binary characters ex: ( 40-8d-5c-1c-5a-50 ) = 12x4=48 Bit address
1st 3 - Hexadecimals ( 40-8d-5c ) are known as:
OEM identifier
Last 3 - Hexadecimals ( 1c-5a-50 )
Unique identifier
CRC stands for what?
Cyclic Redundancy Check ( verifies data is good )
All “F’s” address ( FF-FF-FF-FF-FF-FF ) is a :
Broadcast domain ( sends to all machines on the network )
Domain that know a one specific mac address is:
Unicast domain ( Only sends to one Single Machine )
Logical Address
Is considered a Virtual Address, doesn’t physically exist
IP addressing
The unique identifying number assigned to every device connected to the internet
IP Packets never travel by themselves, they are always incapsulated by a:
Frame
IP Packets never Change but:
Frames do
Some Port numbers ( ex: 80-1694 ) are unique to applications:
80 - Internet or web page ( HTTP )
20 and 21 - are for FTP
Port numbers can be up to:
0 - 65535, they direct packet traffic between the source and destination computers
What and how many port numbers are reserved ( or well known ports )?
1st 1024
Routers look at _____ not MAC addresses.
IP addresses
Every router has one of these and based on the network information of the packet, where to actually send the data:
Routing Table
TCP, which makes sure data gets from PC to PC completely stands for:
Transmission Control Protocol ( Connection oriented )
2 big pieces of TCP are:
Sequencing number and Acknowledgement Number
What protocol is connectionless, just sends data and hopes:
UDP ( User Datagram Protocol ) used for videos and gaming
How does the network software know how to reassemble a file?
Sequencing numbers
This hardware device Generates, receives, and destroys frames:
NIC network interface card
Packets come from what layer:
Layer 3 or Network Layer
Segments and sequencing take place and come from what layer:
Layer 4 or Transport layer
What is & describes physical addressing, and the rules about creating and transmitting frames:
MAC ( Media Access Control )
Mediums and Cablings are also known as:
Topologies
MAC addresses use hexadecimal values of:
0-9 and A-F only
2 types of Topologies are:
Physical - how a network is laid out.
Logical - Explains how data is sent between them.
What is the oldest Topology computers share the same bandwidth and utilize “Drop Downs” or one single trunk
Bus Topology
IBM Token Ring - all computers are connected in a ring:
Ring Topology
Computers are plugged into a hub / switch in the center of the computers
Star Topology
Most popular Topology used today
Star-Bus / or Hybrid Topology
Where all hosts are connected to all host at the same time and is great for Wireless networks.
Mesh Topology (or Mess)
Mesh Topologies have __________ which when a cable breaks between 2 computers, it doesn’t affect the connection between the other machines.
Fault tolerance
large Partially Mesh networks use________ for better connectivity
Extenders
What is the Electronic Circuit Flow of Frames
Logical Topology
Examples of a broadcast IP address:
192.255.255.255 or 192.168.255.255 or 255.255.255.255
