Cisco CCNA mock exam questions sample test – Question 144

.Which layer in the Open Systems Interconnection (OSI) model defines an Internet Protocol (IP) address that helps in selecting the route to the destination?

A. Data Link
B. Network
C. Application
D. Transport

Correct Answer: B

Explanation:
The Network layer in the OSI model defines a logical address that helps select the route to the destination. Logical addresses, such as IP addresses or IPX-SPX addresses, are used
by routers to forward the packets to the destination. This is accomplished systematically by comparing the destination address with the network addresses listed in the routing table.
The logical layout of the network is also defined at this layer. The Network layer is primarily concerned with logical addressing, routing, and path determination.
Protocol data units (PDUs) are called packets at the Network layer. The information that is applied at this layer, which consists of IP addresses, is used in the routing process.
The Data Link layer does not define an IP address. This layer ensures the reliable transmission of data across a network and defines the Media Access Control (MAC) address, which
defines the physical device addressing. This layer also defines the format of the header and trailer.
Protocol data units (PDUs) are called frames at the Data Link layer. The information that is applied at this layer, which consists of MAC addresses, is used in the switching process.
The application layer does not define an IP address. The application layer is responsible for interacting directly with the application and provides application services, such as e-mail,
FTP, and Telnet. It also defines the user authentication process.
The Transport layer does not define an IP address. The Transport layer is responsible for the error-free and sequential delivery of data. This layer is used to manage data
transmission between devices, a process known as flow control.
Protocol data units (PDUs) are called segments at the Transport layer, where the two protocols TCP and UDP operate. Windowing, which is the real-time management of the number
of packets that can be received without an acknowledgement, is handled by TCP at this layer.
Objective:
Network Fundamentals
Sub-Objective:
Compare and contrast OSI and TCP/IP models
References:
Cisco Documentation > Internetworking Technology Handbook > Internetworking Basics>Internet Protocols