FreeBSD Operating System

Упражнение 1:

Номер 1

What is false about the parity bit while asynchronous communication?

Ответ:

(1) The parity bit is set to 0 if the character contains an odd number of bits

(2) To detect any transmission errors, this character is encoded with even parity

(3) If a single bit is corrupted during transmission, the character will arrive with odd parity

(4) Odd parity detects an error for the receiver

Номер 2

What means a long sequence of high level bits while asynchronous communication?

Ответ:

(1) It signals that data is coming

(2) It signals that the line is idle

(3) It signals that any transmission errors were detected

(4) Asynchronous communication is not configured

Номер 3

What detects any transmission errors while asynchronous communication?

Ответ:

(1) A sequence of high level bits

(2) A start bit

(3) A stop bit

(4) A parity bit

Упражнение 2:

Номер 1

What is false about synchronous communication?

Ответ:

(1) It transmits data in blocks

(2) Each block is preceded by one or two SYN characters

(3) SYN characters tell the receiver that that the line is idle

(4) SYN characters enable the receiver to determine the correct orientation of the bits in the data

Номер 2

What is false about hardware handshaking?

Ответ:

(1) Modem raises CTS (Clear to Send) when it’s ready to accept input

(2) Computer asserts RTS (Request to send) when it wants to send data

(3) Modem works in duplex mode

(4) RTS is needed to switch the modem into send mode

Номер 3

What is false about software handshaking?

Ответ:

(1) Modem sends a character (X-off) when the buffer is full

(2) Modem sends a character (X-on) when there is space in the buffer again

(3) You can also use this method on a terminal to temporarily stop the display of a lot of data, and then restart it

(4) Software handshaking is asymmetrical

Упражнение 3:

Номер 1

What is false about modem protocol V.90?

Ответ:

(1) The actual speed of the connection doesn't depend on the telephone line quality

(2) It only works when the other end of the link is a digital (ISDN) connection

(3) It is only suitable for connection to a large ISP site

(4) V.90 pushes modem technology to the limit

Номер 2

What is false about data compression while modem connection?

Ответ:

(1) It increases the data rate

(2) It decreases latency

(3) Data spends more time in the modems being compressed and uncompressed

(4) You usually have a choice of data compression

Номер 3

Which of the following factors has the least impact on the speed of modem connection?

Ответ:

(1) Modem vendor

(2) Protocol

(3) Use of data compression

(4) Telephone line quality

Упражнение 4:

Номер 1

What if false about SLIP?

Ответ:

(1) SLIP supports only IP

(2) It is older than PPP

(3) It performs authentication

(4) It may be available where PPP isn’t

Номер 2

What if false about PPP?

Ответ:

(1) It dials and establishes a phone connection if necessary

(2) It supports only IP

(3) It performs authentication

(4) It’s used on many DSL links

Номер 3

What if false about PPP?

Ответ:

(1) It performs negotiation to decide what kind of protocol to use over the link

(2) It can perform line quality monitoring

(3) It's able to handle multiple protocols simultaneously

(4) It can't handle non-Internet protocols such as X.25, SNA and Novell’s IPX

Упражнение 5:

Номер 1

Which kind of connection can't be used to set up a PPP connection between the two systems.

Ответ:

(1) satellite connection

(2) dialup modem

(3) an ISDN link

(4) a DSL link

Номер 2

What two PPP processes negotiate about?

Ответ:

(1) protocol

(2) authentication protocols

(3) f network interface to use for this connection

(4) IP address

Номер 3

What is the right order of steps to set up a PPP connection?

Ответ:

(1) Establish routes; set up a serial connection between systems; start PPP; PPP processes negotiate details

(2) Set up a serial connection between systems; start PPP; PPP processes negotiate details; establish routes

(3) Establish routes; set up a serial connection between systems; PPP processes negotiate details; start PPP

(4) Set up a serial connection between systems; PPP processes negotiate details; establish routes; start PPP

Упражнение 6:

Номер 1

Which feature of the link while PPP negotiation means: "request this feature"?

Ответ:

(1) accept

(2) deny

(3) enable

(4) disable

Номер 2

Which feature of the link while PPP negotiation means: "if the other side requests this feature, use it"?

Ответ:

(1) accept

(2) deny

(3) enable

(4) disable

Номер 3

Which feature of the link while PPP negotiation means: "if the other side requests this feature, refuse it.’’"?

Ответ:

(1) accept

(2) deny

(3) enable

(4) disable

Упражнение 7:

Номер 1

What is the reason of the situation: sometimes the PPP connection works, and sometimes it doesn’t?

Ответ:

(1) You configured your end correctly. It's a usual situation

(2) If you configured your end incorrectly and both ends wait for the other end to start

(3) If you configured your end incorrectly and both ends fire away, place your demands, and listen for the other one to reply

(4) If you configured your end incorrectly and one side initiates negotiations before the other

Номер 2

Which algorithm of data compression compresses only header, but not the data itself?

Ответ:

(1) Van Jacobson

(2) deflate

(3) Predictor 1

(4) BSD compression

Номер 3

What net mask should be chosen for PPP connection interface?

Ответ:

(1) 0.0.0.0

(2) 255.255.0.0

(3) 255.255.255.0

(4) 255.255.255.255

Упражнение 8:

Номер 1

What are the results of the command "$ ppp -ddial papchap"?

Ответ:

(1) This version dials immediately

(2) As soon as you attempt to send data to the Net, it dials automatically

(3) This version keeps the connection up regardless of whether traffic is passing or not

(4) User PPP stays in the background

Номер 2

What are the results of the command "$ ppp -auto papchap"?

Ответ:

(1) This version dials immediately

(2) As soon as you attempt to send data to the Net, it dials automatically

(3) This version keeps the connection up regardless of whether traffic is passing or not

(4) This only makes sense for static addresses or when you know that no IP connections remain alive after the line disconnects

Номер 3

What are the results of the command "$ ppp -background papchap"?

Ответ:

(1) This version dials immediately

(2) As soon as you attempt to send data to the Net, it dials automatically

(3) After the idle timeout period, the user PPP process disconnects and exits

(4) User PPP stays in the background

Упражнение 9:

Номер 1

What is false about kernel PPP?

Ответ:

(1) To run PPP in the kernel is more efficient and theoretically less prone to error

(2) The configuration files for kernel PPP are in the same directory as the user PPP configuration files

(3) It's necessary set up your own ./.ppprc file

(4) Kernel PPP uses a daemon called pppd to monitor the line when it is active

Номер 2

What is false about kernel PPP?

Ответ:

(1) Kernel PPP interface names start with ppp followed by a number

(2) Each concurrent link needs own kernel ppp interface name

(3) You need to specifically build a kernel for the ppp interface

(4) You can no longer check for ppp support with the ifconfig command

Номер 3

What is false about kernel PPP?

Ответ:

(1) Kernel PPP used to provide a number of build options to enable some features

(2) The options to enable features are set by default

(3) When kernel PPP starts, it reads its configuration from the file /etc/ppp/options

(4) All options are required to run pppd

Упражнение 10:

Номер 1

What is false about DNS?

Ответ:

(1) The Domain Name System is a distributed database

(2) The Domain Name System converts between names and IP addresses

(3) The daemon that performs the resolution is called named

(4) DNS generates a lot of network traffic

Номер 2

What is false about DNS?

Ответ:

(1) FreeBSD allows you to use both /etc/hosts and DNS

(2) BIND is the most common implementation of DNS

(3) DNS causes a dial-on-demand system to dial all the time

(4) The file /etc/hosts contains a list of IP addresses and the corresponding host names

Номер 3

What is false about DNS?

Ответ:

(1) DNS provides the information needed to connect to remote systems in the form of Resource Records

(2) FreeBSD doesn't allow you to use both /etc/hosts and DNS

(3) The daemon that performs the resolution is called named

(4) The Domain Name System is a distributed database

Упражнение 11:

Номер 1

Which of the Resource Records provides a translation from IP address to name?

Ответ:

(1) A

(2) SOA

(3) CNAME

(4) PTR

Номер 2

Which of the Resource Records translates host names to IP addresses?

Ответ:

(1) A

(2) SOA

(3) CNAME

(4) PTR

Номер 3

Which of the Resource Records defines zones, which roughly correspond to domains?

Ответ:

(1) A

(2) SOA

(3) CNAME

(4) PTR

Упражнение 12:

Номер 1

What is false about caching-only name server?

Ответ:

(1) It makes queries to other systems

(2) It saves the information locally

(3) If a program makes the same request again it presents the results much more quickly on subsequent requests

(4) It works when you have your own domain

Номер 2

What is false about functional name servers?

Ответ:

(1) It will work when you have your own domain

(2) It doesn’t have any information of its own, but it stores the results of any queries it makes to other systems

(3) It needs a zone file to work

(4) It needs a reverse lookup zone to work

Номер 3

Which field in the SOA record specifies the length of time that remote name servers should cache records from this zone?

Ответ:

(1) IN

(2) SOA

(3) TTL

(4) MX

Упражнение 13:

Номер 1

Which parameter in the SOA record specifies the time to wait if an attempt to load the zone fails?

Ответ:

(1) Negative cache expiry time

(2) The expire time

(3) The retry time

(4) The refresh time

Номер 2

Which parameter in the SOA record specifies the time after which a slave name server will drop the information about a zone if it has not been able to reload it from the master name server?

Ответ:

(1) Negative cache expiry time

(2) The expire time

(3) The retry time

(4) The refresh time

Номер 3

Which parameter in the SOA record specifies the time after which a remote name server will check whether the zone configuration has changed?

Ответ:

(1) Negative cache expiry time

(2) The expire time

(3) The retry time

(4) The refresh time

FreeBSD Operating System - тест 21