Examen

Question 1

Protocol layering, packet switching, routing and data streaming are the principles on which:

Answer 1

Computer Networks are based

Question 2

The computers and other devices that use the network for communication proposes are referred to as:

Answer 2

Hosts

Question 3

This is the delay that occurs after a send operation is executed before data starts to arrive at the destination computer in network performance

Answer 3

Latency

Question 4

This term is used to refer to any computer or switching device attached to a network

Answer 4

Node

Question 5

This is the speed at which data can be transferred between two computers in the network once transmission has begun.

Answer 5

Data transfer rate

Question 6

This is a single communication subsystem providing communication between all of the hosts that are connected to it, where the internet is constructed form many subnets.

Answer 6

The Internet

Question 7

They carry messages at lower speeds between nodes that
are often in different organizations and may be separated by
large distances.

Answer 7

Wide Area Networks (WAN)

Question 8

The end-to-end communication must provide totally errorfree; the detection of communication errors and their
correction is what we call:

Answer 8

Reliability

Question 9

This is a sequence of binary data (an array of bits or bytes) of restricted length, together with addressing information
sufficient to identify the source and destination of computers

Answer 9

The simples form of packet

Question 10

This is a unit of routing (delivering data from one part of the internet to another)

Answer 10

Subnet

Question 11

This is a type of network is based on the high bandwidth copper and fiber optic cabling recently installed in some
towns and cities for the transmission of video, voice and other data over distances up to 50 kilometers.

Answer 11

Metropolitan Area Networks (MANs)

Question 12

This is defined as the ability to meet deadlines when transmitting and processing streams of real-time multimedia
data

Answer 12

Quality of service

Question 13

This is a communication subsystem in which several networks are linked together to provide common data communication facilities that overlay the technologies and
protocols of the individual component networks and the methods used for the interconnection.

Answer 13

Internetworks

Question 14

This is why many network technologies support the simultaneous transmission of messages to several recipients

Answer 14

Multicasting

Question 15

The IEEE 802.16 WiMAX standard is targeted at this class of network. It aims to provide an alternative to wired connections to home and office buildings

Answer 15

Wireless Metropolitan Area Networks (WMANs)

Question 16

This is referred to as the transmission and display of audio and video in real time. It requires much higher bandwidths than most other forms of communication in distributed systems

Answer 16

Streaming

Question 17

They are composed of a number of personal devices such as mobile phones, tablets, digital cameras, music players and so on that are now carried by many people.

Answer 17

Wireless personal area networks
(WPANs)

Question 18

They are generally used to hold the video frames, but because the flow is continuous as opposed to the intermittent traffic generated by typical client-server interactions and are handled somewhat differently

Answer 18

UDP internet packets

Question 19

In this type of network, most mobile phone networks are based on digital wireless network technologies such as the GSM standard, which is used in most countries of the world

Answer 19

Wireless wide area networks (WWANs)

Question 20

They are specifically designed to provide high bandwidth and low latencies and to support quality of service by the reservation of network resources.

Answer 20

ATM Networks

Question 21

This is a transmission technique that involves no switching, everything is transmitted to every node, and it is up to
potential receivers to notice transmissions addressed to them.

Answer 21

Broadcasting

Question 22

In this type of switching, each packet arriving at a node is first stored in memory at the node and then processed by a
program that transmit it on outgoing circuit, which transfers the packet to another node that is closer to its ultimate
destination.

Answer 22

Packet switching

Question 23

Their operation was simple to understand, when a caller dialed a number, the pair of wires from her phone to the local exchange was connected by an automatic switch at the exchange to the pir of wires connected to the other party´s
phone.

Answer 23

Circuit switching

Question 24

This is used to refer to a well-know set of rules and formats to be used for communication between processes in order to perform a given task

Answer 24

The term protocol

Question 25

The task of dividing messages into packets before transmission and reassembling them at the receiving computer is usually performed in the transport layer.

Answer 25

Packet assembly

Question 26

They are software-defined destinations points at a host computer. They are attached to a processes, enabling data transmission to be addressed to a specific process at a destination node.

Answer 26

Ports

Question 27

This is a numeric identifier that uniquely identifies a host computer and enables it to be located by nodes that are responsible for routing data to it.

Answer 27

A network address

Question 28

When a pair of nodes connected to two separate networks need to communicate through another type of network or over an alien protocol, they can do so by constructing a protocol under a scheme of:

Answer 28

Tunneling

Question 29

This is a function that is required in all networks except those LANs, such as the Ethernet, that provide direct connections between all pairs of attached hosts.

Answer 29

Routing

Question 30

A unified addressing scheme between different networks that enables packets to be addressed to any host connected to any subnet is a necessary element to build:

Answer 30

Internetwork

Question 31

This must lend itself to the development of a flexible and efficient routing scheme, but the addresses themselves cannot contain very much of the information needed to route a packet to its destination.

Answer 31

Addressing scheme

Question 32

The determination of routes for the transmission of packets to their destinations is the responsibility of this procedure, which has two parts:

Answer 32

a routing algorithm

Question 33

It is a based upon the permanent allocation of a normal IP address to each mobile host on a subnet in its home domain.

Answer 33

Mobile IP

Question 34

The purpose of this is to monitor and control all communication into and out of a intranet.

Answer 34

A Firewall

Question 35

Message passing between a pair of processes can be supported by two message communication operations

Answer 35

Send and receive operations

Question 36

In this form of communication, the use of the send operation is non-blocking, receive operation can have blocking and non-blocking variants

Answer 36

The asynchronous form of communication

Question 37

We can describe this as the guaranteed to deliver the message despite a reasonable number of packets being dropped or lost

Answer 37

Reliability

Question 38

Both forms of communication (UDP and TCP) use ______, which provides an endpoint for communication between processes

Answer 38

The socket abstaction

Question 39

In this form of communication, the sending and receiving processes synchronize at every message. In this case, both send and receive are blocking operations

Answer 39

The synchronous communication

Question 40

Any process may make use of multiple of these elements to receive messages, but a process cannot share them with other processes on the same computer.

Answer 40

Ports

Question 41

The internet protocols, and the local port pairs define the:

Answer 41

Message destination

Question 42

This consist of transmitting a message between a socket in one process and a socket in another process

Answer 42

Interprocess communication

Question 43

This is sent by UDP is transmitted from a sending process to a receive process without acknowledgment or retries

Answer 43

A datagram

Question 44

Messages may be dropped occasionally, either because of a checksum error or because no buffer space is available at the source or destination, it’s called:

Answer 44

Omission failures

Question 45

This defines reliable communication for channels in terms of two properties: integrity and validity

Answer 45

Failure Mode

Question 46

This was originated from BSD 4.x UNIX and provides the abstraction of a stream of bytes to which data may be written and from which data may be read

Answer 46

The API to the TCP Protocol

Question 47

This assume that when a pair of processes are establishing a connection, one of them plays the client role and another plays the server role, but thereafter they could be peers

Answer 47

The API for stream communication

Question 48

The TCP protocol uses an acknowledgement scheme. If the sender does not receive an acknowledgement with a time out, it retransmit the message and this performed when:

Answer 48

Lost messages

Question 49

The TCP protocol attempts to match the speeds of the processes that read from and write to a stream, this is called:

Answer 49

Flow control

Question 50

These items transmitted in messages can be data values of many different types and not all computers store primitive values such as integers in the same order.

Answer 50

The individual primitive data

Question 51

This is the process of taking a collection of data items and assembling or disassembling (respectively) into a form suitable for transmission in a message.

Answer 51

Marshalling and Unmarshalling

Question 52

They are three alternative approaches to external data representation

Answer 52

XML, CORBA and Java´s object serialization

Question 53

The first one was designed for defining the appearance of web pages while the second one was designed for writing structured documents for the web

Answer 53

HTML and XML

Question 54

They are tagged with ‘markup’ strings. The tags are used to describe the logical structure of the data and to associate attribute-value pairs with logical structures.

Answer 54

XML data items

Question 55

XML is _____ in the sense that users can define their own tags, in contrast to HTML, which uses a fixed set of tags

Answer 55

Extensible

Question 56

This is a markup language that was defined by the World Wide Web Consortium (W3C) for general use on the web

Answer 56

XML

Question 57

The structure of an XML document is defined by pairs of these elements enclosed in angle brackets

Answer 57

Tags

Question 58

They define the name of values associate to tags in XML schemes

Answer 58

XML Attributes

Question 59

This is used to enable clients to communicate with web services and for defining the interfaces and other properties of web services

Answer 59

XML Service

Question 60

All the information in XML elements must be expressed as character data. But the question is: how do we represent encrypted elements or secures hashes?

Answer 60

Binary data

Question 61

Every start tag has matched end tag and all tags are correctly nested, these are

Answer 61

Basic rules of XML

Question 62

Every XML document must have this as its first line and must at least specify the version of XML in use (chich is currently 1.0)

Answer 62

Prolog

Question 63

This is a set of names for a collection of element types and attributes that is referenced by a URL

Answer 63

XML Namespace

Question 64

This defines the elements and attributes that can appear in a document, how the elements are nested and the order and number of elements, and whether an element is empty or can include text

Answer 64

XML Schema

Question 65

This protocol is based on a trio of communication primitives: doOperation, getRequested and sendReplay

Answer 65

The request-reply protocol

Question 66

This scheme involves the management of messages and requires that each message have a unique element by which it may be referenced

Answer 66

Messages identifiers

Question 67

As its name indicates. It is a mechanism to call a procedure or a function available on a remote computer

Answer 67

RPC

Question 68

This uses the HTTP protocol to pass information from a client computer to a server computer and uses a small XML vocabulary to describe the nature of requests and responses

Answer 68

XML RPC

Question 69

This specifies a procedure name and parameters in the XML request, and the server returns either a fault or a response in the XML response

Answer 69

XML-RPC client

Question 70

Data model, request structures and response structures are parts of

Answer 70

XML RPC Structure

Question 71

Ther are a simple list of types and content – structs and arrays are the most complex types available

Answer 71

XML RPC parameters