47 Questions
At which layer of the Open Systems Interconnection (OSI) model do the protocols on a typical local area network (LAN) use media access control (MAC) addresses to identify other computers on the network?
Data link
Which of the following organizations developed the Open Systems Interconnection (OSI) model?
International Organization for Standardization (ISO)
Which layer of the Open Systems Interconnection (OSI) model is responsible for the logical addressing of end systems and the routing of datagrams on a network?
Network
On a TCP/IP network, which layers of the Open Systems Interconnection (OSI) model contain protocols that are responsible for encapsulating the data generated by an application, creating the payload for a packet that will be transmitted over a network? (Choose all that apply.)
Data link
Which layer of the Open Systems Interconnection (OSI) model is responsible for translating and formatting information?
Presentation
Which of the following devices typically operates at the Network layer of the OSI model?
Router
Which layer of the Open Systems Interconnection (OSI) model provides an entrance point to the protocol stack for applications?
Application
Which layer of the Open Systems Interconnection (OSI) model is responsible for dialogue control between two communicating end systems?
Session
Some switches can perform functions associated with two layers of the Open Systems Interconnection (OSI) model. Which two of the following layers are often associated with network switching? (Choose all that apply.)
Data link
At which layer of the Open Systems Interconnection (OSI) model are there TCP/IP protocols that can provide either connectionless or connection-oriented services to applications?
Transport
Which of the following layers of the Open Systems Interconnection (OSI) model typically have dedicated physical hardware devices associated with them? (Choose all that apply.)
Physical
At which layer of the Open Systems Interconnection (OSI) model is there a protocol that adds both a header and a footer to the information that is passed down from an upper layer, thus creating a frame?
Data link
Identify the layer of the Open Systems Interconnection (OSI) model that controls the addressing, transmission, and reception of Ethernet frames, and also identify the media access control method that Ethernet uses.
Data link layer: CSMA/CD
At which layer of the OSI model do you find the protocol responsible for the delivery of data to its ultimate destination on an internetwork?
Network
Which of the following is not a protocol operating at the Network layer of the OSI model?
IMAP
Ed is a software developer who has been given the task of creating an application that requires guaranteed delivery of information between end systems. At which layer of the Open Systems Interconnection (OSI) model does the protocol that provides the guaranteed delivery run, and what type of protocol must Ed use?
Transport layer; connection-oriented
Alice is a network administrator designing a new local area network (LAN). She needs to determine the type of cabling and the network topology to implement. Which layers of the Open Systems Interconnection (OSI) model apply to cabling and topology elements?
Physical and Data link layers
Which layers of the Open Systems Interconnection (OSI) model do not have protocols in the TCP/IP suite exclusively dedicated to them? (Choose all that apply.)
Session
The protocols at which layer of the Open Systems Interconnection (OSI) model use port numbers to identify the applications that are the source and the destination of the data in the packets?
Transport
Which of the following is a correct listing of the Open Systems Interconnection (OSI) model layers, in order, from top to bottom?
Application, Presentation, Session, Transport, Network, Data link, Physical.
At which of the Open Systems Interconnection (OSI) model layers do switches and bridges perform their basic functions?
Data link
On a TCP/IP network, flow control is a function implemented in protocols operating at which layer of the Open Systems Interconnection (OSI) model?
Session
Which layer of the Open Systems Interconnection (OSI) model defines the medium, network interfaces, connecting hardware, and signaling methods used on a network?
Physical
Which of the OSI model layers is responsible for syntax translation and compression or encryption?
Presentation
Which layer of the Open Systems Interconnection (OSI) model is responsible for transmitting signals over the network medium?
Physical
Specify the layer of the Open Systems Interconnection (OSI) model at which the Internet Protocol (IP) operates and whether it is connection-oriented or connectionless.
Network; connectionless
An Ethernet network interface adapter provides functions that span which two layers of the Open Systems Interconnection (OSI) model?
Physical and Data link
Which of the following protocols operate at the Application layer of the Open Systems Interconnection (OSI) model? (Choose all that apply.)
HTTP
Which layer of the Open Systems Interconnection (OSI) model would be responsible for converting a text file encoded using EBCDIC on the sending system into ASCII code, when required by the receiving system?
Presentation
Which of the following protocols operates at the Network layer of the OSI model but does not encapsulate data generated by an upper layer protocol for transmission over the network?
ICMP
Which of the following devices run exclusively at the Physical layer of the Open Systems Interconnection (OSI) model? (Choose all that apply.)
Repeaters
Which of the following devices enables two computers to communicate when they are using different protocols at each layer of the Open Systems Interconnection (OSI) reference model?
A gateway
Which of the following best describes the function of a firewall?
A device located between two networks that enables administrators to restrict incoming and outgoing traffic
Which of the following terms is used to describe the method by which a firewall examines the port numbers in Transport layer protocol headers?
Service-dependent filtering
Which of the following physical network devices can conceivably be implemented as software in a computer's operating system? (Choose all that apply.)
Switch
Which of the following switch types immediately forwards frames after looking at only the destination address?
Cut-through
What is something that only a firewall capable of stateful packet inspection can do?
Scan Transport layer header fields for evidence of SYN floods
In its primary functionality, a network-attached storage (NAS) device is most closely associated with which of the following devices?
File server
Which of the following statements about the differences between network-attached storage (NAS) and storage area networks (SANs) are true? (Choose all that apply.)
NAS provides file-level storage access, whereas SAN provides block-level storage access.
Which of the following statements specify advantages of FCoE over the original Fibre Channel standard? (Choose all that apply.)
FCoE uses standard Ethernet networking hardware.
Which of the following are Application layer protocols that network-attached storage (NAS) devices can use to serve shared files to clients on the network? (Choose all that apply.)
CIFS
Which of the following is not one of the advantages of iSCSI over Fibre Channel?
iSCSI includes its own internal flow control mechanism, whereas Fibre Channel does not.
Which of the following is the term for the client that accesses an iSCSI device on a storage area network?
Initiator
Which of the following protocols are included in an iSCSI packet on a storage area network (SAN)? (Choose all that apply.)
IP
Which of the following protocol standards defines a layered implementation that does not correspond to the layers of the Open Systems Interconnection (OSI) model?
PPP
Which of the following prevents packets on a TCP/IP internetwork from being transmitted endlessly from router to router?
Time to live (TTL)
Which of the following is the abbreviation for a network of Internet datacenters supplying end users with localized access to their data?
CDN
Study Notes
OSI Model Layers
- The OSI model has 7 layers: Physical, Data link, Network, Transport, Session, Presentation, and Application
Layer 2: Data Link
- Uses MAC addresses to identify computers on a LAN
- Responsible for media access control
- Ethernet uses CSMA/CD (Carrier Sense Multiple Access with Collision Detection)
Layer 3: Network
- Responsible for logical addressing of end systems and routing of datagrams
- IP (Internet Protocol) operates at this layer
- IP is connectionless
Layer 4: Transport
- Provides reliable data transfer between devices
- TCP (Transmission Control Protocol) operates at this layer
- UDP (User Datagram Protocol) also operates at this layer
- Connection-oriented or connectionless protocols
Layer 5: Session
- Establishes, manages, and terminates connections between applications
- Responsible for dialogue control between communicating end systems
Layer 6: Presentation
- Translates and formats information
- Responsible for syntax translation and compression or encryption
Layer 7: Application
- Provides an entrance point to the protocol stack for applications
- Supports functions such as email, file transfer, and virtual terminals
Other Key Facts
- Routers operate at the Network layer
- Switches operate at the Data link layer
- Hubs and repeaters operate at the Physical layer
- Gateways enable communication between devices using different protocols at each layer
- TCP/IP protocols operate at multiple layers of the OSI model
Networking Appliances, Applications, and Functions
- A firewall is a device that restricts incoming and outgoing traffic between two networks.
- Service-dependent filtering is a method used by firewalls to block traffic based on port numbers.
- Deep packet inspection (DPI) is a method used by firewalls to examine the contents of packets.
- A router is a device that connects multiple networks together and forwards traffic between them.
- A switch is a device that connects multiple devices on a network and forwards traffic between them.
- A hub is a simple network device that connects multiple devices together.
- Network address translation (NAT) is a technique used to allow multiple devices to share a single public IP address.
- Intrusion detection systems (IDSs) are used to monitor network traffic for signs of unauthorized access or attacks.
Switching and Routing
- Cut-through switching is a technique used by switches to forward frames immediately after reading the destination address.
- Store-and-forward switching is a technique used by switches to forward frames after receiving the entire frame.
- Routers operate at the Network layer and use IP addresses to forward packets.
- Switches operate at the Data link layer and use MAC addresses to forward frames.
- Routers can connect multiple networks with different Data link layer protocols and media.
Firewalls and Network Security
- Next-generation firewalls (NGFWs) are firewalls that can perform deep packet inspection and other advanced security features.
- Proxy servers are used to access Internet resources on behalf of a network user.
- Content filtering is a technique used by firewalls to block traffic based on the contents of packets.
- Load balancers are used to distribute incoming traffic among multiple servers.
- Unified threat management (UTM) appliances are devices that provide multiple security features, including firewalling, antivirus, and intrusion prevention.
Storage Area Networks (SANs)
- iSCSI is a protocol used to connect storage devices to a network.
- Fibre Channel is a high-speed protocol used to connect storage devices to a network.
- Fibre Channel over Ethernet (FCoE) is a protocol used to connect storage devices to a network over Ethernet.
- Network-attached storage (NAS) devices are used to provide shared file access to a network.
Internet Access and Voice over IP (VoIP)
- Proxy servers can be used to provide Internet access to a network.
- VoIP gateways are used to connect VoIP phones to the Internet.
- VoIP PBX is a device that connects VoIP phones to a network and provides call management features.
Miscellaneous
- Time to live (TTL) is a field in a packet that prevents packets from being transmitted endlessly from router to router.
- Content delivery networks (CDNs) are networks of data centers that provide localized access to data.
- Control plane policing (CPP) is a feature used to prevent denial-of-service attacks on network devices.
Test your understanding of the Open Systems Interconnection (OSI) reference model, including the layers and protocols used in local area networks (LAN).
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