Section 2: Introduction to networking concepts Flashcards
What does OSI stand for?
Open systems interconnection model
Aside from the number of layers, how are OSI and TCP/IP different models from each other?
OSI is more granular in how it accomplishes data transfer
What does MAC stand for and what is a MAC address?
MAC stands for Media Access Control and a mac address is a 12-digit hexadecimal number assigned to each device connected to a network
Does TCP/IP ‘frame’ information?
Yes, they are generated at layer 2
What does TCP/IP stand for?
Transmission control protocol / internet protocol
What are the layers of TCP/IP?
- From the bottom up:
1. Network Interface
2. Network
3. Transport
4. Application
What are the layers of OSI?
- From the bottom up:
1. Physical
2. Data link
3. Network
4. Transport
5. Session
6. Presentation
7. Application
What is the relationship(s) between layers in OSI and TCP/IP?
- Layers 1 and 2 of OSI correspond to layer 1 of TCP/IP
- Layer 3 of OSI corresponds to layer 2 of TCP/IP
- Layer 4 of OSI corresponds to layer 3 of TCP/IP
- Layers 5/6/7 of OSI correspond to layer 4 of TCP/IP
In TCP/IP, what is the application layer responsible for? What protocols are commonly used in this layer? What number is it?
Communication between nodes. Common protocols include HTTP/HTTPS, secure shell (SSH), and network time protocol (NTP). It is the fourth layer.
In TCP/IP, what is the transport layer responsible for? What protocols are commonly used in this layer? What number is it?
End to end transport of data. Common protocols here are user datagram protocol (UDP), and Transmission control protocol (TCP). It is the third layer.
In TCP/IP, what is the network layer responsible for? What protocols are commonly used in this layer? What number is it?
Defines logical transmissions for the whole network. Common protocols include Internet Protocol (IP), Internet Control Message Protocol (ICMP), and Address Resolution Protocol (ARP). It is layer 3
In TCP/IP, what is the network interface layer responsible for? What number is it?
Establishes how data should be physically sent through the network. It is the first layer.
In OSI, what is the application layer responsible for? What number is it?
Responsible for network applications (like HTTP or FTP) and their production of data to be transferred over the network. It is the seventh layer.
In OSI, what is the presentation layer responsible for? What number is it?
Responsible for translating data over the network as well as encrypting data for security (if encryption is used). It is the sixth layer.
In OSI, what is the sessions layer responsible for? What number is it?
Responsible for connection establishment, session maintenance, and authentication. It is the fifth layer.
In OSI, what is the transport layer responsible for? What number is it?
-
The heart of OSI
- Provides services to the application layer and receives services from the network layer
- Responsible for the reliable delivery of data
- It segments and reassembles data in the correct order for it to be sent to the receiving device
- May also handle the reliable delivery of data and any entries of data that are lost or corrupted
- It is the fourth layer.
In OSI, what is the network layer responsible for? What number is it?
Responsible for transmission of data between hosts in different networks as well as routing of data packets and Implemented through the use of devices like routers and some switches. It is the third layer.
In OSI, what is the data link layer responsible for? What number is it?
Responsible for error free delivery of data to the receiving node or device. A physical way of ensuring data continuity. Implemented through devices such as switches and bridge devices, as well as anything with a network interface (like wireless cards or wired network cards). It is the second layer.
In OSI, what is the physical layer responsible for? What number is it?
Responsible for the physical connections of the devices in a network. Hubs, repeaters, modem devices, physical cabling. It is the first layer.
Describe opening a web page in the OSI model:
- Layer 7: You open a web browser and type an address into the search bar
- Layer 6: Command is encrypted as it is sent (and decrypted by receiving server)
- Layer 5: Establishes the connection between your laptop and websites server and maintains it while you accomplish your tasks on the website
- Layer 4: Data is transferred, segmented, and then numbered. This allows the network to send manageable sizes of information ( about 1,500 bytes max), and then reassembled correctly.
- Layer 3: Receives the segments, and transmits them across the network as packets. Adds source and destination IP addresses to each data packet. The destination IP address will be the router on the network that will move data off the local network. The series of routers between that router and the destination server will determine how the packet is moved across the various networks between them
- Layer 2: Receives the packets and adds physical addressing by adding sender and receiver MAC addresses to each data packet. This information forms a unit called a frame.
- Layer 1: Receives the frames and data and sends them via the local media (wires etc.) to the switches, routers, etc. along the network path.
Name 6 network media devices
Modem, router, bridge, switch, hub, and repeater
What does a modem do?
Sends and receives information. Allows computers to send digital information over analog lines.
What does a router do?
A point of connection between two or more networks. Connects networks to each other.
What does a switch do?
A more complex version of a hub which is used to connect devices in a specific network.
What does a bridge do?
Connects two or more networks.
How is a bridge different from a router?
A bridge does not analyze data. It simply forwards data to the next network, whereas a router will.
What does a repeater do?
Extends a weak signal or general range of a connection
What does a hub do?
A device used to connect a router to a network, takes data packets from router, and sends them to devices connected in the network. A USB hub is an example of a hub.
What are the network media devices associated with the third layer of OSI and why?
Switch and router.
What are the network media devices associated with the second layer of OSI and why?
Modem, switch, and bridge
What are the network media devices associated with the first layer of OSI and why?
Modem, hub, and repeater
What is a host device?
any hardware device that has the capability of permitting access to a network via a user interface, specialized software, network address, protocol stack, or any other means
What does UTP stand for?
Unshielded twisted pair
What are the categories of UTP?
CAT1-CAT6
What is different about a coaxial cable?
Shielded with metal
What is fiber optic?
Type of cable that uses light instead of electricity to transfer data
What are the different modes of fiber optic?
Single-mode and Multi-mode
Which is better for longer distance; single- mode or multi-mode fiber?
Single-mode
What is the IEEE?
Institute of electronic and electrical engineers
What is the difference between 2.5gh and 5gh?
the higher the frequency the higher the bandwidth, but shorter the range
What does ICMP stand for?
internal control message protocol
Describe the command ping
- Sends an internal control message protocol (ICMP) echo request to a host and listens for the reply.
- If the echo is received, it will display the time it took and the time to live (TTL) left.
- Useful for troubleshooting!
Describe the command traceroute
Displays each hop (next router) in a numerical list with the hop’s IP address and the time it takes to receive the packet
- traceroute
for Linux or tracert
for windows
- Need admin privileges