LECTURE 3- NETWORK SERVICES

Question 1

Give examples of network services

Answer 1

World Wide Web services, File transfer, File sharing, Internet mail, Remote Administration, Directory services( internet), Automatic Network Access configuration, Network Administration

Question 2

Link the following services with the TCP/IP protocols associated with them:
World Wide Web services, File transfer, File sharing, Internet mail, Remote Administration, Directory services( internet), Automatic Network Access configuration, Network Administration

Answer 2

World Wide Web services-HTTP
File transfer- FTP, TFTP
File sharing-NFS
Internet mail-SMTP, POP3, IMAP
Remote Administration-Telnet
Directory services (internet)-DNS, LDAP
Automatic Network Access configuration- DHCP, Network Administration-SNMP

Question 3

What is remote access?

Answer 3

the ability to access a system or network, whether it’s a personal device or office server, without being physically present.

With a remote access
connection, employees
can access the corporate
remote access server and
log in to the network with
their regular user
account.
• Employees can then use
all the resources that
would be available from
the office desktop
computer

Question 4

What is telecommuting and what are its advantages?

Answer 4

Telecommuting is the ability for an employee to complete work assignments from outside the traditional workplace by using telecommunications tools such as email, phone, chat and video apps.

Telecommuting is attractive to employees because it saves travel time and other costs associated with working in an office.
• It saves the company money as well because office space for telecommuting employees is not required.
• Each modem requires its own separate telephone line.

*See notes for pic

Question 5

What are the benefits of having mobile users

Answer 5

It can be difficult or
impossible to store all the
files needed on a laptop or
notebook computer.
• It is a security threat as
well because the laptop
and its contents could be
physically stolen.
• A better solution is for
mobile users to dial in to
the company LAN.

Question 6

What is terminal emulation?

Answer 6

Terminal emulation is the process of accessing a remote system via a local computer terminal.
• The local terminal runs software that emulates, or mimics, the look of the remote system terminal.
• The local user can type commands and execute programs on the remote system.

Question 7

What are telnet services?

Answer 7

Telnet is the main Internet protocol for creating a connection with a remote machine.
• It gives the user the opportunity to be on one computer system and do
work on another.

Question 8

What security considerations does telnet have?

Answer 8

– Hacking
– Password guessing
– Denial of Service (DoS) attacks
– Packet sniffing (viewable text data)

Question 9

Differentiate between remote access and remote administration.

Answer 9

• Remote access - Network users and network administrators can access
  network services remotely.
• Remote administration – Only network administrators can manage, control and configure network remotely.

Question 10

What are directory services?

Answer 10

A directory service provides
system administrators with
centralized control of all users and resources across the entire network.
• Shared resources are published
to the directory
• Users can locate and access them without ever knowing on which machine the resources physically reside.
• The files, directories, and
shares that users access from a single point can be distributed across multiple servers and locations using distributed directory and replication services

Question 11

What are the advantages of having directory services?

Answer 11

• They provide the ability to
organize information and help simplify the management of the network by providing a standard interface for common system administration tasks.

Question 12

What components make up mail services?

Answer 12

– Mail Transfer Agent (MTA)
– Mail User Agent (MUA)
– Mail Delivery Agent (MDA)

Question 13

What is the name of the most popular MTA used on UNIX and Linux servers?

Answer 13

Sendmail. Sendmail relies on Simple Mail Transfer Protocol (SMTP) to receive mail from clients and forward mail to other mail servers.

Question 14

What are some popular Mail User Agents(mail clients)?

Answer 14

Microsoft Outlook, Eudora,
and Pine.
• MUAs can compose and send mail to MTAs, such as Sendmail.

Question 15

What is an MDA

Answer 15

a program that is responsible for routing received mail to the appropriate mailboxes on the mail server.

Question 16

How do remote mail clients retrieve mail from a mail server?

Answer 16

They use Post
Office Protocol version 3 (POP3) or Internet Message Access
Protocol (IMAP).

Question 17

Describe the printing services offered by NOS

Answer 17

• When a user decides to print in a networked printing environment, the job is sent to the appropriate queue for the selected printer.
• Print queues stack the
incoming print jobs and
service them using a “First In, First Out” (FIFO) order.
• It is placed at the end of the list of waiting jobs and is printed after all other previous jobs before it.

Question 18

Describe the file sharing services offered by NOS

Answer 18

• File sharing is often done
using the File Transfer
Protocol (FTP) within a
home or office network.
• Peer-to-peer networking is popular among home
users, but the technology
has yet to be deployed as
a widespread business
solution.
• Peer-to-peer protocols
work without a central
server. 
• Many organizations make files available to remote employees, customers, and to the general public via File Transfer Protocol (FTP).
• FTP servers can be configured to allow anonymous access.
• FTP is a session-oriented
protocol (Clients must open a session with the server, authenticate, and then perform an action such as download or upload.)

Question 19

Describe web services offered by NOS

Answer 19

The Web is based on a client server model.
• Clients attempt to establish TCP sessions with web servers.
• Once established, a client can request data from the server.
• The Hypertext Transfer Protocol (HTTP) typically governs client requests and server transfers.
• Web client software includes GUI web browsers, such as Netscape Navigator and Internet Explorer.

Question 20

How can one configure an intranet so that only on-site users can access the intranet services?

Answer 20

Using an internet firewall

Question 21

What are some possible advantages of having an extranet?

Answer 21

Advantages of an extranet for a company could be email, customer support, e-commerce, and program
sharing.

Question 22

Describe scripts

Answer 22

• Scripts are considered to be much simpler than the
standard programs and applications found in a NOS.
• The operating system sequentially processes the lines of code in a script file whenever the file is run.
• Most scripts are designed to execute from the top of the file to the bottom without requiring any input from the user.
• Most average NOS users will not create and execute
their own scripts.
• The majority of scripting is performed by system
administrators and experienced users.

Question 23

Give examples of scripting languages

Answer 23

– Visual Basic script (VBScript)
– JavaScript
– Linux shell scripting
– Perl, PHP, TCL, REXX, and Python

Question 24

Give examples to demonstrate common scenarios where scripts are an appropriate solution

Answer 24

– Logging on to the NOS
– Printing messages to the screen
– Installing software
– Automating complicated commands

Question 25

What is a host name and what are the two parts of a hostname?

Answer 25

The Internet name that the DNS resolves to the IP address is also called the Hostname.
• The first part of the hostname is called the Machine Name and the
second part is called the Domain Name.

Question 26

Describe the leasing mechanism used by a DHCP

Answer 26

• This mechanism allocates an IP address
for a specific time period, releases it
and then assigns a new IP address. This allows for recovery and the ability to automatically renew network IP addresses

Question 27

What is a domain and what are the advantages of having domains?

Answer 27

A domain is a logical
grouping of networked
computers that share a
central directory or database.
• Domains have several
advantages:
– Centralized administration since all user information is stored centrally.
– A single logon process that enables users to access network resources as well as specify permissions that control who can and cannot access these services.
– The ability to expand a network to extremely large sizes throughout the world.

Question 28

Map the following functions of computer
networks with appropriate network service(s):
i. Resource sharing
ii. Communication

Answer 28

i. Resource sharing – Printing services, files
sharing
ii. Communication – mailing services, web services, telecommuting, mobile user