CISCO CCNA 200-301 Q82

A newly implemented IP-based video conferencing application is causing the network to slow down. Which OSI layer needs to be addressed to resolve the problem?

A. Layer 1
B. Layer 2
C. Layer 3
D. Layer 4
E. Layer 5
F. Layer 6
G. Layer 7

Correct Answer: A

You need to address Open System Interconnect (OSI) Layer 1, the Physical layer, to resolve the problem. IP-based video conferencing applications are bandwidth- intensive and may cause the network to slow down unless there is enough bandwidth to ensure proper network operation. To resolve bandwidth problems, you may need to switch to a higher capacity network backbone, which may require a change of cabling or media types, such as fiber optics. Cabling and network media types are defined at OSI Layer 1.

The seven layers of the OSI model are as follows, in descending order from Layer 7 to Layer 1:

– Application: Interacts directly with the application. It provides application services, such as e-mail and File Transfer Protocol (FTP).

– Presentation: Enables coding and conversion functions for application layer data. The Presentation layer converts data into a format that is acceptable by the application layer. The formatting and encryption of data is done at this layer.

– Session: Creates, manages, and terminates sessions between communicating nodes. The session layer handles the service requests and responses that take place between different hosts.

– Transport: Delivers data sequentially and without errors. This layer manages data transmission between devices, a process known as flow control. The Transport layer protocols are Transmission Control Protocol (TCP) and User Datagram Protocol (UDP).

– Network: Defines the network address or the Internet Protocol (IP) address, which is then used by the routers to forward the packets.

– Data Link: Ensures the reliable delivery of data to the physical address of the destination.

– Physical layer: This layer includes the physical equipment involved in the data transfer, such as the cables and switches. It also include fiber optic, wireless, and Ethernet.