Networking Concepts (3)

Question 1

At which of the Open Systems Interconnection (OSI) model layers do switches and bridges perform their basic functions?

Physical

Data link

Network

Answer 1

Data link

Switches and bridges are involved in local area network (LAN) communications only and therefore operate at the data link layer

Question 2

Flow control is a function implemented in protocols operating at which layer of the Open Systems Interconnection (OSI) model?

Presentation

Session

Transport

Answer 2

Transport

Flow control is a process that adjusts the transmission rate of a protocol based on the capability of the receiver. If the receiving system becomes overwhelmed by incoming data, the sender dynamically reduces the transmission rate. In the TCP/IP protocol suite, Transmission Control Protocol (TCP) is responsible for implementing flow control. TCP runs at the transport layer. None of the other layers listed have TCP/IP protocols that provide flow control

Question 3

Which layer of the Open Systems Interconnection (OSI) model defines the medium, network interfaces, connecting hardware, and signaling methods used on a network?

Physical

Data link

Network

Answer 3

Physical

The physical layer of the OSI model defines the standards for the physical and mechanical characteristics of a network, such as cabling (copper and fiber), connecting hardware (hubs and switches), and signaling methods (analog and digital). All of the other layers are not involved in the mechanical characteristics of the network

Question 4

Which of the OSI model layers is responsible for syntax translation and compression or encryption?

Data link

Session

Presentation

Answer 4

Presentation

The presentation layer provides a syntax translation service that enables two computers to communicate, despite their use of different bit-encoding methods. This translation service also enables systems using compressed or encrypted data to communicate with each other

Question 5

Which layer of the Open Systems Interconnection (OSI) model is responsible for transmitting signals over the network medium?

Physical

Data link

Network

Answer 5

Physical

The physical layer of the OSI model defines the functions specific to the network medium and the transmission and reception of signals. All of the other layers are implemented in software and do not physically send or receive signals

Question 6

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; connection-oriented

Network; connectionless

Transport; connection-oriented

Answer 6

Network; connectionless

IP is a connectionless protocol that operates at the network layer of the OSI model. There are no connection-oriented protocols at this layer. The protocols at the transport layer include Transmission Control Protocol (TCP), which is connection-oriented, and User Datagram Protocol (UDP), which is connectionless

Question 7

An Ethernet network interface adapter provides functions that span which two layers of the Open Systems Interconnection (OSI) model?

Physical and data link

Data link and network

Network and transport

Answer 7

Physical and data link

A network interface adapter functions at the data link layer by encapsulating network layer data for transmission over the network. It provides physical layer functions by providing the connection to the network medium and generating the appropriate signals for transmission

Question 8

Which of the following protocols operate at the application layer of the Open Systems Interconnection (OSI) model? (Choose all correct answers.)

HTTP

SNMP

ICMP

IGMP

UDP

Answer 8

HTTP

SNMP

Hypertext Transfer Protocol (HTTP) and Simple Network Management Protocol (SNMP) operate at the application layer. Internet Control Message Protocol (ICMP) and Internet Group Management Protocol (IGMP) both operate at the network layer. User Datagram Protocol (UDP) operates at the transport layer

Question 9

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?

Application

Presentation

Session

Answer 9

Presentation

The presentation layer of the OSI model is responsible for translating different kinds of syntax, including text-encoding systems, such as EBCDIC and ASCII. The application, session, and physical layers do not perform this function

Question 10

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?

UDP

ARP

ICMP

Answer 10

ICMP

Internet Control Message Protocol (ICMP) operates at the network layer by sending operational and error messages. It does not encapsulate upper layer protocol data. Internet Protocol (IP) operates at the network layer, but it does encapsulate transport layer protocol data. Transmission Control Protocol (TCP) and User Datagram Protocol (UDP) are transport layer protocols that encapsulate upper layer protocol data. Address Resolution Protocol (ARP) does not encapsulate upper layer protocol data, but it is a data link layer protocol

Question 11

Which of the following could be a valid MAC address for a network interface adapter?

10.124.25.43

FF:FF:FF:FF:FF:FF

00:1A:6B:31:9A:4E

Answer 11

00:1A:6B:31:9A:4E

A media access control (MAC) address is a six-byte hexadecimal value, with the bytes separated by colons, as in 00:1A:6B:31:9A:4E. Option A, 10.124.25.43, is all decimals and uses periods; this is an IPv4 address. Option B, FF:FF:FF:FF:FF:FF, is a valid MAC address, but this value is reserved for use as a broadcast address. Option D, 03:AE:16:3H:5B:11, is not a valid hexadecimal address, which should contain only numerals and the letters A to F. Option E, fe80::89a5:9e4d:a9d0:9ed7, is too long for a MAC address; this is a valid IPv6 address

Question 12

Which of the following TCP/IP parameters, configured on an end system, specifies the Internet Protocol (IP) address of a router on the local network that provides access to other networks?

WINS Server Addresses

Default Gateway

DNS Server Addresses

Answer 12

Default Gateway

The Default Gateway parameter specifies the address of the local router that the end system should use to access other networks. The WINS Server Addresses and DNS Server Addresses parameters are used to resolve names to IP addresses. There is no such parameter as Subnet Gateway

Question 13

Which of the following services enables computers on a private IPv4 network to access the Internet using a registered IP address?

DHCP

NAT

DNS

NTP

Answer 13

NAT

Network Address Translation (NAT) is a service that enables computers with unregistered IP addresses to access the Internet by substituting a registered address in packets as they pass through a router. The Dynamic Host Configuration Protocol (DHCP) is an IP address allocation service. Domain Name System (DNS) resolves domain and hostnames into IP addresses, and Network Time Protocol (NTP) enables network devices to synchronize their time settings

Question 14

Which of the following protocols prevents network switching loops from occurring by shutting down redundant links until they are needed?

RIP

STP

VLAN

Answer 14

STP

The Spanning Tree Protocol (STP) prevents packets from endlessly looping from switch to switch due to redundant links. Creating redundant links is a good preventive against switch failure, but packets transmitted over multiple links can circulate from switch to switch infinitely. STP creates a database of switching links and shuts down the redundant ones until they are needed. Routing Information Protocol (RIP) propagates routing table information. A virtual local area network (VLAN) is an organizational tool that operates within switches by creating multiple broadcast domains. Network Address Translation (NAT) is a routing method that enables private networks to share registered IP addresses

Question 15

Which of the following are techniques used in traffic shaping to prevent networks from being overwhelmed by data transmissions? (Choose all correct answers.)

Bandwidth throttling

Rate limiting

Broadcast storming

Network address translation

Answer 15

Bandwidth throttling

Rate limiting

Bandwidth throttling is a traffic shaping technique that prevents specified data streams from transmitting too many packets. Rate limiting is a traffic shaping technique that controls the transmission rate of sending systems. A broadcast storm is a type of network switching loop. Network address translation is a method by which private networks can share registered IP addresses. Neither of these last two is a traffic shaping technique

Question 16

Which of the following best defines the concept of the dual stack?

A computer with two network interface adapters

A computer with two installed operating systems

A computer with two sets of networking protocols

Answer 16

A computer with two sets of networking protocols

A dual stack is an IP implementation that includes both IPv4 and IPv6 protocol stacks, operating simultaneously. A computer with two network adapters or connections to two network segments is often called multihomed. A computer with two installed operating systems is called a dual-boot system

Question 17

An enterprise network has been designed with individual departmental switches because in most cases, the devices in a specific department exchange network traffic with other devices in the same department. Each of the departmental switches is also connected to a host switch, which enables devices to communicate with other departments. Which of the following terms describes this switching architecture?

Distributed switching

Port forwarding

Traffic shaping

Answer 17

Distributed switching

Distributed switching describes a hierarchical switching architecture in which remote switches (in this case departmental switches) handle most of the network traffic, with a host switch used only for traffic between the remote locations. Port forwarding is a routing method that redirects traffic intended for one IP address and port number to another. Traffic shaping is a series of techniques that optimize the allocation of network bandwidth. Neighbor discovery is an IPv6 technique used to find addresses of devices and services on the local network

Question 18

Which of the following terms refers to methods by which network traffic is prioritized to prevent applications from suffering faults due to network congestion?

Dynamic routing

VLANs

QoS

Answer 18

QoS

Quality of service (QoS) is a general term that refers to various mechanisms for prioritizing network traffic so that applications or data streams requiring a certain level of performance are not negatively affected by lower-priority transmissions. Port forwarding is a routing method that redirects traffic intended for one IP address and port number to another. Dynamic routing is a method by which routing tables are automatically updated with new information as the routing fabric of an internetwork changes. Virtual local area networks (VLANs) are a means for partitioning a broadcast domain into discrete units that are functionally equivalent to physical LANs

Question 19

Which of the following statements about Routing Information Protocol version 1 (RIPv1) is true? (Choose all correct answers.)

RIPv1 broadcasts the entire contents of the routing table every 30 seconds.

RIPv1 advertises the subnet mask along with the destination network.

RIPv1 broadcasts only the elements in the routing table that have changed every 60 seconds.

RIPv1 does not include the subnet mask in its network advertisements.

Answer 19

RIPv1 broadcasts the entire contents of the routing table every 30 seconds.

RIPv1 does not include the subnet mask in its network advertisements.

Routers that are running the RIPv1 routing protocol broadcast their entire routing tables every 30 seconds, regardless of whether there has been a change in the network. RIP v1 does not include the subnet mask in its updates, so it does not support subnetting

Question 20

Which of the following is an example of a circuit-switched network connection, as opposed to a packet-switched network connection?

Two wireless computers using an ad hoc topology

A landline voice telephone call

A smartphone connecting to a cellular tower

Answer 20

A landline voice telephone call

A circuit switched network connection requires a dedicated physical connection between the communicating devices. In a landline telephone call, a dedicated circuit is established between the two callers, which remains in place for the entire duration of the call. Wireless computers in an ad hoc topology and computers connected to a wired LAN use packet switching instead. A smartphone connection uses cell switching

Question 21

Which of the following mechanisms for prioritizing network traffic uses a 6-bit classification identifier in the Internet Protocol (IP) header?

Diffserv

CoS

Traffic shaping

Answer 21

Diffserv

Differentiated services (Diffserv) is a mechanism that provides quality of service on a network by classifying traffic types using a 6-bit value in the differentiated services (DS) field of the IP header. Class of Service (CoS) is a similar mechanism that operates at the data link layer by adding a 3-bit Priority Code Point (PCP) value to the Ethernet frame. Traffic shaping is a means of prioritizing network traffic that typically works by delaying packets at the application layer. Quality of service (QoS) is an umbrella term that encompasses a variety of network traffic prioritization mechanisms

Question 22

Which of the following is a network layer protocol that uses ICMPv6 messages to locate routers, DNS servers, and other nodes on an IPv6 network?

BGP

NDP

OSPF

Answer 22

NDP

The Neighbor Discovery Protocol (NDP) is a network layer protocol that defines five new Internet Control Message Protocol version 6 (ICMPv6) packet types, which enable IPv6 systems to locate resources on the network, such as routers and DNS servers, as well as autoconfigure and detect duplicate IPv6 addresses. Border Gateway Protocol (BGP) is an exterior gateway protocol that is designed to exchange routing information among autonomous systems. Open Shortest Path First (OSPF) is a link state routing protocol that enables routers to exchange routing table information. Power over Ethernet (PoE) is a general term for standards defining mechanisms for power delivery over Ethernet cables, along with data signals

Question 23

Which of the following is a protocol that identifies VLANs by inserting a 32-bit field in the Ethernet frame?

IEEE 802.1P

IEEE 802.1Q

IEEE 802.1X

Answer 23

IEEE 802.1Q

IEEE 802.1Q is a standard that defines a mechanism (called Ethernet trunking by some manufacturers) that identifies the virtual local area network (VLAN) to which a packet belongs by inserting an extra 32-bit field into its Ethernet frame. IEEE 802.1P is a standard that defines a mechanism for implementing quality of service (QoS) at the data link layer by adding a 3-bit field into Ethernet frames. IEEE 802.1X is a standard defining an authentication mechanism called port-based network access control (PNAC). IEEE 802.1AB is a standard defining the Link Layer Discovery Protocol (LLDP)

Question 24

Which of the following is not an advantage of packet switching over circuit switching?

Packets can be transmitted out of order.

Packets can take different routes to the destination.

Packets can be stored temporarily in the event of network congestion.

Answer 24

Packets can be stored temporarily in the event of network congestion.

On a packet-switched network, packets can take different routes to the destination, can be transmitted out of order, and can be routed around network congestion. The packets are then reassembled into a complete message once all of them reach the destination. Temporary message storage is an advantage of circuit switching networks

Question 25

Which of the following statements about static routing are true? (Choose all correct answers.)

Static routes are manually configured routes that administrators must add, modify, or delete when a change in the network occurs.

Static routes are automatically added to the routing table by routing protocols when a new network path becomes available.

Static routes adapt to changes in the network infrastructure automatically.

Static routes are a recommended solution for small internetworks with a single path to each destination network.

Answer 25

Static routes are manually configured routes that administrators must add, modify, or delete when a change in the network occurs.

Static routes are a recommended solution for small internetworks with a single path to each destination network.

Administrators must manually add, modify, or delete static routes when a change in a network occurs. For this reason, static routes are not recommended for use in large internetworks where there are multiple paths to each destination network. Static routes are not automatically added by routing protocols and do not adapt to changes in a network