Topic #10: Application Layer Services and Examples

Question 1

These identify applications and application layer services that are the source and destination of data

Answer 1

Port Numbers

Question 1

What addressing scheme does the transport layer use?

Answer 1

Port Numbers

Question 2

Port Number for the Domain Name System

Answer 2

TCP/UDP port 53

Question 3

Port Number for HTTP

Answer 3

TCP port 80

Question 4

Port number for SMTP

Answer 4

TCP port 25

Question 5

Port number for POP

Answer 5

UDP port 110

Question 6

Port number for Telnet

Answer 6

TCP port 23

Question 7

Port number for DHCP

Answer 7

UDP port 67

Question 8

Port for FTP

Answer 8

TCP Ports 20 and 21

Question 9

Two things that make DNS Work

Answer 9

DNS Protocol and DNS Resolver

Question 10

This defines the automated service that matches the resource names with the required numeric network address

Answer 10

DNS protocol

Question 11

This supports the name resolution for the other network applications and other services that need it

Answer 11

DNS resolver

Question 12

Record type that means an end device

Answer 12

A

Question 13

Record type which means an authoritative name server

Answer 13

NS

Question 14

Record type that is a canonical name for an alias

Answer 14

CNAME

Question 15

Record type that means Mail Exchange Record

Answer 15

MX

Question 16

Steps in using WWW Service and HTTP

Answer 16

• URL is typed in the address bar
• browser checks with the DNS server and converts it to an IP address
• Connects to the server requested
• Using HTTP the browser sends a GET request for the desired HTML document
• the server sends the HTML for the webpage
• browser interprets the HTML code and formats the page

Question 17

The email client when people compose e-mails.

Answer 17

Mail User Agent

Question 18

Applications and services for MUA to use

Answer 18

POP or POP3
SMTP

Question 19

What protocol to use when Sending email?

Answer 19

SMTP Protocol

Question 20

What protocol to use when receiving emails?

Answer 20

POP Protocol

Question 21

This is used to forward emails, receives emails from the Mail User Agent, uses SMTP to route emails between servers and passes email to the MDA for final delivery

Answer 21

Mail Transfer Agent

Question 22

Receives messages from MUA or from the MTA on another server

Answer 22

Mail Delivery Agent

Question 23

Command in the SMTP protocol that identifies the SMTP client process to the SMTP server process

Answer 23

HELO

Question 24

Command in the SMTP protocol that is a newer version of HELO

Answer 24

EHLO

Question 25

Command in the SMTP protocol that identifies the sender

Answer 25

MAIL FROM

Question 26

Command in the SMTP protocol that identifies the recipient

Answer 26

RCPT TO

Question 27

This is another commonly used application layer protocol that was used to develop to allow file transfers between client and a server

Answer 27

File Transfer Protocol

Question 27

Command in the SMTP Protocol that identifies the body of the message

Answer 27

DATA

Question 28

FTP Process

Answer 28

- Client opens first connection to the server for control traffic - Client opens second connection for control traffic - Gets data

Question 29

this protocol enables devices to obtain IP addresses, subnet masks, gateways, DNS server information and etc.

Answer 29

Dynamic Host Configuration Protocol

Question 30

DHCP IP address hosting process

Answer 30

- assigns an IP address that is not being used from a range of available IP addresses - if host logs off or losses power, IP address is returned to the pool to be reassigned to another host if needed

Question 31

This protocol allows servers to share their resources with clients

Answer 31

Server Message Block

Question 32

What SMB does

Answer 32

-start, authenticate and terminate sessions - control file and printer access - allow applications to send/receive messages to/from another device

Question 33

Gnutella protocol packet type for device discovery

Answer 33

ping

Question 34

Gnutella protocol packet type as a reply to a ping

Answer 34

pong

Question 35

Gnutella protocol packet type for a file location

Answer 35

query

Question 36

Gnutella protocol packet type as a reply to a query

Answer 36

query hit

Question 37

Gnutella protocol packet type as a download request

Answer 37

push

Question 38

Disadvantage of using Telnet Service

Answer 38

Data is not encrypted

Question 39

Oldest application layer protocols

Answer 39

Telnet

Question 40

Secure version of Telnet

Answer 40

Secure Shell (SSH)

Question 41

This protocol allows users to emulate text-based terminal devices over the network using network software

Answer 41

Telnet

Question 42

Telnet Protocol Command that enables the user to request that a response appear on the terminal screen to indicate that the VTY session is active

Answer 42

AYT (Are You There)

Question 43

Telnet Protocol Command that deletes all text from the current line

Answer 43

EL (Erase Line)

Question 44

Suspends the process to which the virtual terminal is connected.

Answer 44

IP (Interrupt Process)

Question 45

These are computer programs with which the user interacts and initiate data transfer process at the user's request

Answer 45

Applications

Question 46

These are background programs that provide the connection between application layer and the lower layers of the networking model

Answer 46

Services

Question 47

It allows P2P applications to search for shared resources on peers

Answer 47

Gnutella

Question 48

These were created to convert the numeric IP addressed into a simple, recognizable name

Answer 48

Domain Names