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Network Models
CCNA Network Models
Network Models | |
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List the 7 layers of the OSI model from highest to lowest. | Application Presentation Session Transport Network Data Link Physical |
Briefly describe the Application layer | This is where the end user interacts with the network. It ensures the remote communication is available and is responsible for agreeing on basic rules of communication such as data integrity, privacy, and presence or absence of error recovery features |
Briefly describe the Presentation layer | Answers the question of “how will data be presented.” Data encryption happens at this layer. An example of a presentation layer issue would be opening a pdf in an a non-PDF-friendly app |
Briefly describe the Session layer | The session layer handles the creation, maintenance, and teardown of the communications channel (the session) that exist between our two communicators. |
Briefly describe the Transport layer | The main purpose of L4 (transport layer) is to establish a logical end-to-end connection between two systems. Both the TCP (transmission control protocol) and the UDP (user datagram protocol) are doing some important work at this layer. |
Briefly describe the Network layer | This is where routers do their job. They answer two basic questions: - What valid paths exist from here to where we need to go – our destination? - Of those valid paths, which is the best path to use to get there? |
What is TCP? | Transmission Control Protocol |
What is UDP | User Datagram Protocol |
Briefly describe the Data Link layer | This is where switches work. Switches use MAC addresses (Media Access Control addresses) to direct traffic to specific devices. |
What are 4 other names for MAC addresses? | Layer 2 address Hardware address Burned-In Address (BIA) Physical Address |
Briefly describe the Physical layer | All data is eventually converted to ones and zeroes being sent across the physical layer. Anything dealing with the network cable or the standards in use – including pins, connectors, and the electric current used – is running at the physical layer. |
What layer of the OSI model deals with segments? | Segments are the data unit for the TRANSPORT layer. |
What layer of the OSI model deals with packets? | Packets are the data unit for the NETWORK layer. |
What layer of the OSI model deals with frames? | Frames are the data unit for the DATA LINK layer. |
What layer of the OSI model deals with bits (ones and zeros)? | Bits are the data unit for the PHYSICAL layer. |
Describe how headers work as data travels through the OSI model? | As data heads down the OSI model, each layer (except L1) adds a header that will be removed by the same layer at the other end of the session. Headers are layer-specific. |
Which OSI layer attaches a Trailer in addition to a header? | L2, the Data Link layer |
What is PDU? | A Protocol Data Unit is the combination of data and a layer-specific header. They are usually referred to by the layer number (L7 PD, L6 PDU, etc.) |
What is the main difference between the OSI Model and the TCP/IP Model? | In the TCP/IP model, the top three layers of the OSI Model (application, presentation and session) are all grouped into one layer called the Application Layer. |
What does “OSI” stand for in the OSI Model? | Open Systems Interconnection |
The HTTP Protocol runs at which layer of the OSI Model? | Application L7 |
The FTP Protocol runs at which layer of the OSI Model? | Application L7 |
The Telnet Protocol runs at which layer of the OSI Model? | Application L7 |
The SSH Protocol runs at which layer of the OSI Model? | Session L5 |
The TCP Protocol runs at which layer of the OSI Model? | Transport L4 |
The UDP Protocol runs at which layer of the OSI Model? | Transport L4 |
The IPv4 and IPv6 Protocol runs at which layer of the OSI Model? | Network L3 |
The IPSec Protocol runs at which layer of the OSI Model? | Network L3 |
The ICMP Protocol runs at which layer of the OSI Model? | Network L3 |
The PPP Protocol runs at which layer of the OSI Model? | Data Link L2 |
The MPLS Protocol runs at which layer of the OSI Model? | Data Link L2 |
The Ethernet Protocol runs at which layer of the OSI Model? | Physical L1 |