Chapter 9 Flashcards
1
Q
Electronic Mail (SMTP, MIME, IMAP)
A
-
Message Format:
- Components: Consists of headers and body.
- Headers: Include fields such as From, To, Subject, Date.
- Body: Contains the actual content of the email, may include plain text or HTML.
- MIME: Multipurpose Internet Mail Extensions standard allows non-text attachments (audio, video, images).
2
Q
Message Transfer:
A
-
SMTP: Simple Mail Transfer Protocol used for sending emails.
- Process: Email client connects to an SMTP server to send a message.
- Reliability: Uses a store-and-forward mechanism to ensure delivery.
-
IMAP: Internet Message Access Protocol used for retrieving messages.
- Functionality: Allows users to view and manage emails directly on the server.
- Synchronization: Keeps emails consistent across multiple devices.
3
Q
Mail Reader:
A
-
Client Software: Examples include Outlook, Thunderbird, web-based interfaces.
- Capabilities: Supports reading, composing, and managing emails.
- IMAP vs. POP3: IMAP allows accessing emails from multiple devices, while POP3 downloads and removes them from the server.
4
Q
World Wide Web (HTTP)
A
-
Request Messages:
- Format: Includes request line (method, URL, HTTP version), headers, and an optional body.
- Methods: Common methods include GET, POST, PUT, DELETE.
- Usage: Methods define the action to be performed on the specified resource.
5
Q
Response Messages:
A
-
Structure: Contains a status line (HTTP version, status code, reason phrase), headers, and an optional body.
- Status Codes: Indicate the result of the request, such as 200 (OK), 404 (Not Found), 500 (Server Error).
- Headers: Provide metadata about the response, such as content type and length.
6
Q
Uniform Resource Identifiers (URIs):
A
-
Purpose: Identifies resources on the web.
- Types: Includes URLs (locator) and URNs (name).
- Syntax: Typically consists of a scheme, authority, path, query, and fragment.
6
Q
TCP Connections:
A
-
Connection Management: HTTP relies on TCP for reliable communication.
- Lifecycle: Involves connection establishment, data transfer, and connection termination.
- Performance: Persistent connections reduce overhead by reusing TCP connections for multiple requests.
7
Q
Caching:
A
-
Mechanism: Stores copies of responses to reduce latency and load.
- Control: HTTP headers like Cache-Control and ETag manage caching behavior.
- Benefits: Improves performance and reduces bandwidth usage.
8
Q
Web Services
A
-
Custom Application Protocols (WSDL, SOAP):
- WSDL: Web Services Description Language defines service endpoints and operations.
- SOAP: Simple Object Access Protocol facilitates structured message exchange.
- Usage: Common in enterprise environments for integrating disparate systems.
9
Q
Defining Application Protocols:
A
-
Specification: Detailed description of how applications interact over the network.
- Components: Includes message formats, communication sequences, and error handling.
- Example: REST (Representational State Transfer) uses standard HTTP methods for CRUD operations.
10
Q
Defining Transport Protocols:
A
-
Role: Ensures reliable and efficient data transfer.
- Examples: TCP for reliability, UDP for low-latency applications.
- Adaptation: Protocols may be customized to meet specific application requirements.
11
Q
Standardizing Web Service Protocols:
A
-
Purpose: Facilitates interoperability between different systems and platforms.
- Organizations: Bodies like W3C and OASIS define and promote standards.
- Impact: Standardization ensures compatibility and broad adoption.
12
Q
A Generic Application Protocol (REST):
A
-
Principles: Uses standard HTTP methods and status codes.
- Architectural Style: Emphasizes stateless communication and resource-based interactions.
- Benefits: Simplifies development and integration of web services.
13
Q
From Web Services to Cloud Services:
A
-
Evolution: Shift from traditional web services to cloud-based services.
- Characteristics: Cloud services offer scalability, flexibility, and managed infrastructure.
- Examples: Platforms like AWS, Google Cloud, and Azure provide a range of services from computing to storage .
14
Q
Session Description Protocol (SDP)
A
- Purpose: Defines the format for describing multimedia communication sessions for announcements and invitations.
-
Components:
- Session name
- Purpose
- Media types
- Transport protocols
- Format information
- Network information
- Timing details
- Usage: Commonly used with protocols like SIP and RTSP for multimedia sessions.
15
Q
Session Initiation Protocol (SIP)
A
- Purpose: Manages the initiation, maintenance, and termination of real-time sessions across IP networks.
-
Functions:
- User location
- Session setup
- Session management
- Session teardown
-
Components:
- User agents
- Proxy servers
- Redirect servers
- Registrars
16
Q
H.323
A
- Purpose: Standard for multimedia communication over packet-based networks, particularly the Internet.
-
Components:
- Terminals
- Gateways
- Gatekeepers
- Multipoint Control Units (MCUs)
- Protocols: Integrates protocols for call signaling, control, multimedia transport, and bandwidth management.
17
Q
Resource Allocation Challenges
A
- Bandwidth: Ensuring sufficient bandwidth for multimedia streams.
- Latency: Minimizing delay for real-time communication.
- Jitter: Reducing variations in packet arrival times.
- Loss: Managing packet loss to maintain quality.
18
Q
Resource Allocation Techniques
A
- Integrated Services (IntServ): Guarantees bandwidth for applications by reserving network resources.
- Differentiated Services (DiffServ): Provides quality of service by classifying and managing network traffic.
- Admission Control: Decides whether to accept a new flow based on available resources.
- Resource Reservation Protocol (RSVP): Used by IntServ for reserving resources across a network.
19
Q
Real-Time Transport Protocol (RTP)
A
- Purpose: Designed for delivering audio and video over IP networks.
-
Components:
- Sequence numbers
- Timestamps
- Payload type identifiers
- Source identifiers
20
Q
Real-Time Control Protocol (RTCP)
A
- Function: Works alongside RTP to provide quality feedback and synchronization between media streams.
- Features: Reports on transmission statistics and session participants.
21
Q
Multimedia Transport Considerations
A
- UDP Usage: Preferred for low-latency applications despite lack of reliability.
- TCP Considerations: Provides reliable delivery but may introduce unacceptable delays for real-time media.
22
Q
Purpose of DNS
A
- Function: Maps user-friendly names to router-friendly addresses.
23
Q
DNS Terminology
A
- Name Space: Defines the set of possible names (flat or hierarchical).
- Bindings: Associations between names and values (e.g., addresses).
- Resolution Mechanism: Procedure to return a value for a given name.
- Name Server: A specific implementation of a resolution mechanism available on a network.
24
**Domain Hierarchy**
- **Hierarchical Name Space:** Used by DNS to handle the large size of the Internet.
- **Early Internet:** Used a central authority and flat table (HOSTS.TXT) for name-to-address bindings.
- **Modern DNS:** Employs a hierarchical name space and distributed system.
25
**Zones**
- **Definition:** Subtrees of the domain hierarchy managed by an administrative authority.
- **Example:** Top-level zone managed by ICANN, sub-zones managed by organizations like Princeton University.
26
**Name Servers**
- **Function:** Store and manage zone information.
- **Redundancy:** Each zone implemented in two or more name servers for reliability.
- **Hierarchy:** Hierarchy of name servers mirrors the domain hierarchy.
27
**Resource Records Format**
- **Components:** (Name, Value, Type, Class, TTL).
- **Type Field:** Specifies interpretation of the Value (e.g., A for IP address).
- **Class Field:** Typically denotes the Internet (IN).
- **TTL (Time to Live):** Indicates how long the record is valid for caching purposes.
28
**Resource Records Types**
- **A Records:** Name-to-address mappings.
- **NS Records:** Domain name for a host running a name server.
- **CNAME Records:** Canonical names for aliases.
- **MX Records:** Domain name for a mail server.
