Networking Cert

Which of the following functions are performed at the Physical layer of the OSI model? Conversation identification Enabling network services Provisioning environments where you can run network applications Moving data across network cables Data translation

Moving data across network cables Explanation The Physical layer is concerned with how to transmit data and how to connect network hosts.

Which of the following tasks is associated with the Session layer? Acknowledgment coordination Transmission synchronization Host ID number assignment Connection establishment

Connection establishment Explanation Connection establishment is controlled through Session layer protocols.

Which of the following are included as part of Data Link layer specifications? (Select two.) Synchronizing individual bits as they are transmitted through the network. Controlling how messages are propagated through the network. Composing electrical signals as they pass through the transmission medium. Identifying physical network devices.

Controlling how messages are propagated through the network. Identifying physical network devices. Explanation The Data Link layer controls device identification on networks, as well as how messages travel through the network (the logical topology). The other functions listed here are performed by the Physical layer.

What is the basic purpose of the OSI Physical layer? Coordinates rules for routing packets. Coordinates rules for transmitting bits. Defines basic physical structures, such as disks. Coordinates rules for managing network servers.

Coordinates rules for transmitting bits. Explanation The OSI Physical layer coordinates rules for transmitting bits.

Which of the following functions are performed by the OSI Transport layer? (Select three.) Consistent data formatting between dissimilar systems Data segmentation and reassembly Control media access, logical topology, and device identification Reliable message delivery Path identification and selection Format packets for delivery through the media End-to-end flow control

Data segmentation and reassembly Reliable message delivery End-to-end flow control Explanation The Transport layer is responsible for breaking upper-layer data into segments and allowing reliable communications through end-to-end flow control, error detection, and error correction. Message transmission through media is performed at the Physical layer. Media access, logical topology, and device identification occurs at the Data Link layer. Path identification and selection is a function of the Network layer. Data formatting is performed at the Presentation layer.

Which of the following are functions of the MAC sublayer? (Select two.) Defining a unique hardware address for each device on the network Mapping hardware addresses to link-layer addresses Creating routing tables based on MAC addresses Letting devices on the network have access to the LAN

Defining a unique hardware address for each device on the network Letting devices on the network have access to the LAN Explanation The MAC sublayer defines a unique MAC or data-link address for each device on the network. This address is usually assigned by the manufacturer. The MAC sublayer also provides devices with access to the network media.

In the OSI model, which of the following functions are performed at the Application layer? (Select all that apply.) Data translation Conversation identification Enabling communication between network clients and services Integrating network functionality into the host operating system

Enabling communication between network clients and services Integrating network functionality into the host operating system Explanation The Application layer enables network services and integrates network functionality into the host operating system. Applications actually run above the OSI Application layer. Conversation identification is accomplished at the Session layer through connection or transaction ID numbers. Data translation is performed at the Presentation layer.

The Data Link Layer of the OSI model is comprised of two sublayers. What are they? (Select two.) LLC SAN DLC LAT MAC

LLC MAC Explanation The Data Link layer is split into the following sublayers: The Logical Link Control (LLC) Sublayer, which provides the operating system link to the device driver. The Media Access Control (MAC) Sublayer, which translates generic network requests into device-specific terms.

In the OSI model, what is the primary function of the Network layer? Ensures that packets are delivered with no loss or duplication Routes messages between networks Transmits data frames Allows applications to establish, use, and end a connection

Routes messages between networks Explanation The Network layer is responsible for routing messages between networks.

In the OSI model, which of the following functions are performed at the Presentation layer? (Select two.) Specify data format (such as file formats) Handle general network access, flow control, and error recovery Encrypt and compress data Maintain separate client connections Provide network services Transmit data frames

Specify data format (such as file formats) Encrypt and compress data Explanation The Presentation layer encrypts data, changes and converts character sets, and compresses data. File formats (such as .jpg, .wmv, and .wav) are part of the Presentation layer. The Application layer provides network services. The Session layer maintains separate client connections through session IDs and maintains those sessions. Flow control and error detection are provided at both the Transport layer and the Data Link layer. Frame transmission occurs at the Physical layer.

Which OSI model layer is responsible for guaranteeing reliable message delivery? Data Link Session Application Transport

Transport Explanation The Transport layer is responsible for connection services that provide reliable message delivery through error detection and correction mechanisms. Specifically, the TCP protocol provides these services. The Application layer integrates network functionality into the host operating system and enables network services. The Session layer's primary function is managing the sessions in which data is transferred. The Data Link layer defines the rules and procedures for hosts as they access the Physical layer.

During TCP/IP communications between two network hosts, information is encapsulated on the sending host and decapsulated on the receiving host using the OSI model. Match the information format on the left with the appropriate layer of the OSI model on the right. (Not all layers have a matching information format.) Bank: Bits Segments Packets Frames Layers: Transport Layer Session Layer Network Layer Data Link Layer Physical Layer

Transport Layer: Segments Session Layer: None Network Layer: Packets Data Link Layer: Frames Physical Layer: Bits