Lesson 2 Flashcards
1
Q
Types of messages exchanges in App-layer protocols
A
Request and Response
2
Q
Example of Proprietary Protocols
A
Skype
3
Q
Define (6) App-layer protocol
A
- Types of Messages exchanged
- Message Syntax
- Message Semantics
- Rules for when and how processes send and respond to messages
- Open Protocols
- Proprietary Protocols
4
Q
Example of Network Apps
A
- Web
- Text Messaging
- Remote Log In
- P2P File Sharing
- Multi-user network games
- Streaming Stored Video
- Voice Over IP
- Real-Time Video Conferencing
- Social Networking
- Search
5
Q
Example of Streaming Stored Video
A
Youtube, Hulu, Netflix
6
Q
Example of Voice Over IP
A
Skype
7
Q
2 Application Architectures
A
Client-Server
Peer-To-Peer
8
Q
it includes both IP address and port numbers associated with progress on host
A
Identifier
9
Q
Port Numbers
HTTP Server:
Mail Server:
A
HTTP Server: 80
Mail Server: 25
10
Q
Transport Services an App need
A
- Data Integrity
- Timing
- Throughput
- Security
11
Q
it is a measure of how many units of information a system can process in a given amount of time.
A
throughput
12
Q
What is throughput
A
it is a measure of how many units of information a system can process in a given amount of time.
13
Q
What do you call when valuable or sensitive information on a computer is compromised due to theft, human error, viruses, malware, or power failure
A
Data Loss
14
Q
File Transfer in Throughput
A
Elastic Throughput
15
Q
Email in throughput
A
Elastic Throughput
16
Q
Web Documents in Throughput
A
Elastic
17
Q
Throughput: Real-time Audio (kbps)
A
5kbps-1mbps
18
Q
Throughput: Real-time Video (kbps)
A
10kbps-5mbps
19
Q
Throughput: Stored Audio
A
5kbps-1mbps
20
Q
Throughput: Stored Video
A
10kbps-5mbps
21
Q
Throughput: Interactive Games
A
Few kbps up
22
Q
Throughput: Text Messaging
A
Elastic
23
Q
DATA LOSS: FILE TRANSFER
A
No Loss
24
Q
DATA LOSS: Email
A
No Loss
25
DATA LOSS: Web Documents
No Loss
26
DATA LOSS: Real-Time Audio/Video
Loss-Tolerant
27
DATA LOSS: Stored Audio/Video
Loss-Tolerant
28
DATA LOSS: Interactive Games
Loss-Tolerant
29
DATA LOSS: Text Messaging
No Loss
30
3 TCP SERVICES
1. Reliable Transport
2. Flow Control
3. Congestion Control
31
Does TCP Service provide Timing and Minimum throughput?
No
32
In UDP Service, is data transfer unreliable?
Yes
33
UDP Service does not provide the following (8):
1. Reliability
2. Flow Control
3. Congestion Control
4. Timing
5. Throughput
6. Guarantee
7. Security
8. Connection Set Up
34
It define the language that network applications speak to fulfill user requests
Application Layer protocol
35
Refers to HTML file, JPEG Image, Java Applet, Audio File
Object
36
Webpage consist of _________ like HTML-FILE
Objects
37
is a browser that requests, receives using HTTP protocol
client
38
sends objects in response to requests,
Server
39
It uses HTTP Protocol
Server
40
They use to initiate TCP connection to HTTP server in Port 80
HTTP client
41
is HTTP is STATELESS?
YES
42
HTTP client request message contains what?
URL (or objects)
43
What is the format of HTTP request message?
ASCII
44
3 GENERAL FORMAT OF HTTP REQUEST MESSAGES
Request Line
Header Line
Body
45
4 TYPES OF HTTP REQUEST MESSAGES
Post Method
Get Method
Head Method
Put Method
46
TYPES OF HTTP REQUEST MESSAGES:
- Web page often includes form input
- User input sent from client to server in entity body of _________ request message
POST METHOD
47
Include user data in URL field of HTTP request message (following a’?’)
Get Method
48
Requests headers (only) that would be retired if specific URL were requested with an HTTP GET method
Head Method
49
- Uploads a new file (object) to server
Put Method
50
Completely replaces file that exists at specified URL with content in entity body of POST HTTP request message
Put method
51
TWO TYPES OF HTTP CONNECTIONS
1. Non-persistent HTTP
2. Persistent HTTP
52
Sequence of Non-persistent HTTP
1. TCP connection opened
2. At most one object sent over TCP connection
3. TCP connection closed
53
Sequence of Persistent HTTP
1. TCP connection opened to a server
2. Multiple Objects can be sent over single TCP connection between client, and that server
3. TCP connection closed
54
Only one Object can be sent over TCP connection
NON-PERSISTENT HTTP
55
Multiple objects can be sent
PERSISTENT HTTP
56
5 RESPONSE STATUS CODES
404
400
505
301
200 OK
57
RESPONSE STATUS CODE 404
404 NOT FOUND requested documented not found on this server
58
RESPONSE STATUS CODE 400
400 Bad Request: requested messages not understood by server
59
RESPONSE STATUS CODE 505
505 HTTP Version Not Supported
60
RESPONSE STATUS CODE 301
301 Moved Permanently: Requested object moved, new location specified later in this message (in Location: Field)
61
RESPONSE STATUS CODE 200 OK
Request succeeded, request object later in this message
62
These are use by web sites and client browsers to maintain some state between transactions
Cookies
63
3 Uses of Cookies
1. Track user behavior on a given website (first party cookies)
2. Track user behavior across multiple websites (Third party cookies) without user ever choosing to visit tracker site
3. Tracking may be invisible to
64
Cookies can be used in (4)
1. Authorization
2. Shopping cats
3. Recommendations
4. User session state (web email)
65
Cookie is also known as?
Unique ID
66
Common Identity is also known as?
Cookie Value
67
Third party persistent cookies is also known as?
Tracking Cookies
68
FOUR COMPONENTS OF COOKIES
1. Cookie header line of HTTP response message
2. Cookie hear line in next HTTP request message
3. Cookie file kept on user’s host, managed by user’s browser
4. Back-end database at web site
69
Satisfy client request without involving origin server
Web caches
70
WEB CACHES: What is the Average rate from browsers to origin servers?
15/sec
71
WEB CACHES: What is the Average data rate to browsers?
1.50 Mbps
72
Web Caches are also known as?
Proxy Servers
73
3 COMPONENTS OF ELECTROMAGNETIC MAIL
1. User Agents
2. Mail Servers
3. Simple Mail Transfer Protocol (SMTP)
74
Other term for User Agent
Mail Reader
75
it contains Incoming messages for user
Mailbox
76
it means outgoing mail messages
Message Queue
77
4. EXAMPLE OF ELECTRONIC MAIL USER AGENT
1. Outlook
2. Thunderbird
3. iPhone
4. Mail Client
78
SMTP use ___________ connection
Persistent
79
It is Between mail servers to sent mail messages
SMTP
80
They Send mail server
Client
81
They Receive mail server
Server
82
What SMTP server uses to determine end of message?
CRLF
83
SMTP:PUSH
HTTP:
PULL
84
The transfer of email messages from client to server happen on what port?
PORT 25
85
3 PHASES OF TRANSFER
1. Handshaking (Greeting)
2. Transfer of messages
3. Closure
86
The Format used for commands is
ASCII text
87
Protocol for exchanging email messages
SMTP
88
Standard for text message format
RFC 822
89
entered by user, formatted by local user agent
Header lines
90
Format of Header lines
To:
From:
Subject:
91
Where the “message” ASCII characters only
Body
92
Fields giving info about data
Headers
93
Info (Payload) being communicated
Data
94
MAIL ACCESS PROTOCOLS
1, POP
2. IMAP
3. HTTP
95
CLIENT COMMANDS: declares username
User
96
CLIENT COMMANDS: password
Pass
97
SERVER RESPONSES
+ OK
- ERR
98
TRANSACTION PHASE
List
Retr
Dele
Quit
99
list message numbers
List
100
retrieve message by number
Retr
101
delete
Dele
102
Keeps all messages in one place: at server
IMAP
103
Where does IMAP store all messages?
server
104
implemented in hierarchy of many name servers
Distributed Database
105
4 DNS SERVICES
1. Hostname to IP address translation
2. Host aliasing
3. Mail server aliasing
4. Load distribution
106
3 SUB BRANCHES OF ROOT DNS SERVERS
com DNS servers
org DNS servers
edu DNS servers
107
Organization’s own DNS server(s), providing authoritative hostname to IP mappings for organizations named hosts.
AUTHORITATIVE DNS SERVERS
108
RR format
(name, value, type, TTL)
109
4 FLAGS
1. Query or reply
2. Recursion desired
3. Recursion available
4. Reply is authoritative
110
- No always-on server
- Arbitrary end systems directly communicate
- Peers are intermittently connected and changed IP addresses
PURE P2P ARCHITECTURE
111
EXAMPLE OF PURE P2P ARCHITECTURE
1. File distribution (BitTorrent)
2. Streaming (KanKan)
3. VoIP (Skype)
112
Group of peers exchanging chunks of a file
Torrent
113
Tracks peers participating in torrent
Tracker
114
Peers may come and go
Churn
115
EXAMPLES OF VBR
MPEG 1
MPEG 2
MPEG 4
116
Stores copies of content in CDN nodes
CDN
117
Learn how to build client/server applications that communicate using sockets
SOCKET PROGRAMMING
118
Door between application process and end-end transport protocol
Socket
119
2 Socket types for 2 transport services
UDP and TCP
120
Time for a small packet to travel from client to server and back
RTT
