100-150 Exam Dumps - Cisco CCST Questions and Answers

OSI model

During the data encapsulation process, the Data Link layer of the OSI model is responsible for adding a header that contains MAC addressing information and a trailer used for error checking. The header typically includes the source and destination MAC addresses, while the trailer contains a Frame Check Sequence (FCS) which is used for error detection1.

The Data Link layer ensures that messages are delivered to the proper device on a LAN using hardware addresses and translates messages from the Network layer into bits for the Physical layer to transmit. It also controls how data is placed onto the medium and is received from the medium through the physical hardware.

References :=

The OSI Model – The 7 Layers of Networking Explained in Plain English

OSI Model - Network Direction

Which layer adds both header and trailer to the data?

What is OSI Model | 7 Layers Explained - GeeksforGeeks

Here’s how each protocol aligns with the correct TCP/IP model layer:

TCP (Transmission Control Protocol): This protocol belongs to the Transport layer, which is responsible for providing communication between applications on different hosts1.

IP (Internet Protocol): IP is part of the Internetwork layer, which is tasked with routing packets across network boundaries to their destination1.

FTP (File Transfer Protocol): FTP operates at the Application layer, which supports application and end-user processes. It is used for transferring files over the network1.

Ethernet: While not a protocol within the TCP/IP stack, Ethernet is associated with the Network Interface layer, which corresponds to the link layer of the TCP/IP model and is responsible for the physical transmission of data1.

The TCP/IP model layers are designed to work collaboratively to transmit data from one layer to another, with each layer having specific protocols that perform functions necessary for the data transmission process1.

TCP:

TCP Model Layer: Transport

Explanation: The Transport layer is responsible for end-to-end communication and error handling. TCP (Transmission Control Protocol) operates at this layer to provide reliable, ordered, and error-checked delivery of data.

IP:

TCP Model Layer: Internetwork

Explanation: The Internetwork layer, also known as the Internet layer, is responsible for logical addressing and routing. IP (Internet Protocol) operates at this layer to route packets across networks.

FTP:

TCP Model Layer: Application

Explanation: The Application layer provides network services to applications. FTP (File Transfer Protocol) operates at this layer to transfer files between computers over a network.

Ethernet:

TCP Model Layer: Network

Explanation: The Network layer, also known as the Link layer in the TCP/IP model, is responsible for physical addressing and access to the physical medium. Ethernet operates at this layer to provide the physical and data link functions.

Transport Layer: This layer is responsible for providing communication services directly to the application processes running on different hosts. TCP is a core protocol in this layer.

Internetwork Layer: This layer is responsible for logical addressing, routing, and packet forwarding. IP is the primary protocol for this layer.

Application Layer: This layer interfaces directly with application processes and provides common network services. FTP is an example of a protocol operating in this layer.

Network Layer: In the TCP/IP model, this layer includes both the data link and physical layers of the OSI model. Ethernet is a protocol used in this layer to define network standards and communication protocols at the data link and physical levels.

References:

TCP/IP Model Overview: Cisco TCP/IP Model

Understanding the TCP/IP Model: TCP/IP Layers