The Open Systems Interconnection (OSI) Reference Model

Physical

A communications engineer notices that every time it rains the signal becomes very degraded. Which layer of the OSI model is the engineer most likely troubleshooting?

Layer 2 (Data Link Layer)

A network engineer is designing a network in various offices to create multiple broadcast domains. Each has its own Virtual Local Area Network (VLAN). When configuring these multiple broadcast domains on the switch, the switch will be operating at what layer of the OSI model?

Layer 4

A security engineer configures software-based port security on a hardware firewall. Which OSI model layer identifies the application ports to configure?

Media converter

An engineer uses a type of network adapter to connect a fiber link to a router. The transceiver fits into an optical interface on a layer 3 Ethernet router. Of the choices, which layer 1 implementation does the engineer utilize?

Encapsulation

As information travels down the network stack from the Application layer to the Physical layer, what happens?

Transport Layer

Flow control can be found at which layer of the OSI?

The primary function of the Network layer is to move data around an internetwork using logical network and host IDs.

In the OSI model, what is the primary function of the Network layer?

HTTP functions at the Application layer. Encapsulation happens at the Presentation layer. Session IDs are assigned at the Session layer. Port numbers are assigned at the Transport layer. Routers function at the Network layer. Switches function at the Data Link layer.

Match each networking function or device on the left with its associated OSI model layer on the right.

Transport

TCP and UDP reside at which layer of the OSI model?

A chunk of data with protocol-specific headers added at each OSI layer

What is a Protocol Data Unit (PDU)?

Three-way Handshake

What is required before TCP can begin sending segments?

To add additional data headers for routing and delivery

What is the primary purpose of data encapsulation in network protocols?

Datagram, segment, packet, frame, bits

What is the proper order of data encapsulation?

To filter network traffic by permitting or blocking packets based on IP addresses and other criteria

What is the role of an Access Control List (ACL) at Layer 3 (Network layer) of the OSI model?

The Presentation layer supports data compression and encryption to prepare data for network transmission.

What role does the Presentation layer (layer 6) of the OSI model play in terms of data compression and encryption?

Source hardware address Destination hardware address Checksum for basic error checking

When the Data Link layer performs encapsulation, it adds control information to the payload in the form of header fields. Which of the following are header fields added by the Data Link layer during encapsulation? (Select three.)

802.2

Which 802 working group defines the LLC sublayer of the Data Link Layer?

802.3

Which EEE standard specifics the protocol for CSMA/CD?

Network Layer

Which OSI layer is responsible for logical addressing?

Data Link and Physical Layer

Which OSI layers are responsible for framing data and transmitting the data?

Windowing

Which concept describes transmitting segments before the receiving host acknowledges the data?

Router

Which device will stop broadcasts from propagating the network?

Allow software to run on network speeds

Which is not a benefit to the OSI model?

Metric

Which is used to determine the best path to a destination network?

Presentation Layer

Which layer is responsible for compression and decompression?

Transport

Which layer is responsible for creating a virtual circuit?

Network

Which layer is responsible for routing data packets?

Session Layer

Which layer of the OSI is responsible for dialogue control of applications?

1. Session Layer 2. Presentation Layer 3. Application Layer

Which of the following are layers of the OSI reference model? (Select three.)

1. Bridges 2. Switches 3. Network interface cards (NICs)

Which of the following devices operate at the Data Link layer of the OSI model? (Select three.)

Reliable message delivery Data segmentation and reassembly End-to-end flow control

Which of the following functions are performed by the OSI Transport layer? (Select three.)

The Session layer administers the process of establishing, managing, and terminating a dialog between client and server.

Which of the following statements accurately describes the function of the Session layer (layer 5) in the OSI model?

Bits

Which protocol data unit (PDU) is used to describe data at the Physical layer?

LLC

Which sublayer of the Data Link OSI layer is responsible for identifying Network layer protocols and encapsulating them?

Application, Presentation, and Session

Which three upper layers operate speeds?