Web Server Performance and Load Balancing
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Web Server Performance and Load Balancing

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Questions and Answers

What is the primary purpose of the ISO-OSI model?

  • To provide specific application software for networks
  • To create a single unified networking protocol
  • To benchmark international standardization of computer networking protocols (correct)
  • To ensure all network devices are the same

    • Which layer of the TCP/IP model is responsible for end-to-end transport services between hosts?

  • Application Layer
  • Transport Layer (correct)
  • Link Layer
  • Network Layer

    • What function does the Network Layer serve in the TCP/IP model?

  • Provides access to the physical network
  • Handles session management
  • Manages application interfaces
  • Forwards packets across the network (correct)

    • Which of the following organizations is NOT involved in the standardization of networking protocols?

    <p>NIST</p> Signup and view all the answers

    What is the role of layers in the ISO-OSI model?

    <p>To promote development and flexibility through well-defined interfaces</p> Signup and view all the answers

    What must a computer be connected to in order to access the Internet?

    <p>A router</p> Signup and view all the answers

    What is the primary function of an ISP in relation to local ISPs?

    <p>Charge local ISPs for traffic management</p> Signup and view all the answers

    Which entity is responsible for the management of domain names and IP address space?

    <p>ICANN</p> Signup and view all the answers

    How does a client's browser typically resolve a domain name into an IP address?

    <p>By sending a request to the client's ISP</p> Signup and view all the answers

    What indicates that an answer received by an ISP is not authoritative?

    <p>The answer is marked 'non-authoritative'</p> Signup and view all the answers

    What is the primary purpose of the Domain Name System (DNS)?

    <p>To convert IP addresses into human-readable domain names</p> Signup and view all the answers

    Which part of a Uniform Resource Locator (URL) specifies the resource being accessed?

    <p>Directory/resource</p> Signup and view all the answers

    What occurs if an ISP cannot find the answer to a domain name request in its cache?

    <p>It looks for the information at root servers</p> Signup and view all the answers

    Which characteristic of a web server allows it to handle multiple client requests simultaneously?

    <p>Forking/Multithreading</p> Signup and view all the answers

    What does throughput measure in the context of a web server?

    <p>The rate at which HTTP requests are serviced</p> Signup and view all the answers

    Which method of dynamic load balancing involves mapping to a cluster of servers during address translation?

    <p>DNS Based</p> Signup and view all the answers

    What defines the role of an application server in a web environment?

    <p>Handling transactions between the web server and database</p> Signup and view all the answers

    In a packet-switched network, what do hosts represent?

    <p>The originators and destinations of data packets</p> Signup and view all the answers

    What happens to packets in a 'Best-effort' delivery network when congestion occurs?

    <p>They are discarded</p> Signup and view all the answers

    What can be a source of additional delay in a web server's response time?

    <p>Third Party Services</p> Signup and view all the answers

    Which component is essential for managing a database in a web infrastructure?

    <p>Database Server</p> Signup and view all the answers

    What protocol is foundational for webpage generation?

    <p>HTTP</p> Signup and view all the answers

    What type of cache can significantly reduce web server load?

    <p>Community Proxy Servers</p> Signup and view all the answers

    What is the primary function of a Network Access Storage (NAS)?

    <p>To allow multiple computers to share the same storage space</p> Signup and view all the answers

    Which protocol is NOT typically used to connect to a NAS?

    <p>Cisco Internetwork Operating System</p> Signup and view all the answers

    What is a key advantage of a Storage Area Network (SAN) over a NAS?

    <p>Faster data transfer</p> Signup and view all the answers

    Which of the following is a limitation of a SAN?

    <p>It cannot transfer data over long distances.</p> Signup and view all the answers

    Which operating systems can utilize NAS effectively?

    <p>Any operating systems connected to a LAN</p> Signup and view all the answers

    What management function does an operating system perform?

    <p>Oversees resource allocation and process scheduling</p> Signup and view all the answers

    What characterizes a SAN's data integrity compared to NAS?

    <p>SANs maintain efficient data integrity, backup, and recovery</p> Signup and view all the answers

    Which of the following best describes the Fiber Channel of the SAN?

    <p>It has a maximum effective distance of around 10 km.</p> Signup and view all the answers

    What is the primary function of the link layer in the networking model?

    <p>Encapsulating IP datagrams into frames</p> Signup and view all the answers

    Which of the following correctly describes IPv4 addresses?

    <p>They are 32-bit addresses in dot decimal format.</p> Signup and view all the answers

    What role does the transport layer play in the network communication process?

    <p>It establishes a connection-oriented communication using TCP.</p> Signup and view all the answers

    What is a key difference between TCP and UDP?

    <p>TCP is connection-oriented, whereas UDP is connectionless.</p> Signup and view all the answers

    Which of the following elements is NOT found in an IPv4 header?

    <p>Source port</p> Signup and view all the answers

    Which statement accurately describes the function of the network layer?

    <p>It is responsible for routing datagrams to their destination.</p> Signup and view all the answers

    What kind of addresses do IPv6 utilize compared to IPv4?

    <p>128-bit addresses to accommodate more devices.</p> Signup and view all the answers

    Which layer is responsible for the handshaking process in establishing a connection?

    <p>Transport Layer</p> Signup and view all the answers

    What is typically the binary representation of the IPv4 address 128.0.0.1?

    <p>10000000.00000000.00000000.00000001</p> Signup and view all the answers

    What does TCP stand for in networking?

    <p>Transmission Control Protocol</p> Signup and view all the answers

    Study Notes

    Web Server Characteristics

    • Also known as HTTP Server or Daemon.
    • Continuously listens to client requests and returns the requested file.
    • Handles more than one request at a time, using methods like forking or multithreading.

    Web Server Performance Metrics

    • Throughput: Rate at which HTTP requests are serviced. Measured in HTTP operations per second or Mbps.
    • Latency: Time required to complete a request. Average latency is the average time for handling requests.

    Dynamic Load Balancing

    • Splitting traffic across servers to distribute workload.
    • Methods:
      • DNS Based: Mapping requests to a server cluster in a round-robin fashion during address translation.
      • Dispatcher Based: Routing requests to the server with the least load via a special TCP router.
      • Server Based: Address redirection, which may increase client response time.

    Application Server

    • Handles transactions between the web server and the backend database.
    • Supports different programming and scripting languages.

    Database Server

    • Database management system that utilizes structured query language (SQL) for data manipulation.
    • Offers database connectivity for data access and retrieval.

    E-business Infrastructure Components and Concepts

    • Mainframe and Legacy Systems: Integration between new and older systems is frequently required.
    • Proxies:
      • Reduce network traffic.
      • Enhance privacy and security by acting as firewalls.
      • Contribute to load balancing.
    • Caches:
      • Reduce traffic by storing frequently accessed data for faster retrieval.
      • Can be implemented at different levels, including dedicated community proxy servers.
    • Third-Party Services: Offer additional functionalities such as security, advertising, trust, and escrow services.
      • Can introduce additional delay in the web server response time.

    Other Data Resources

    • Data Warehouses and Data Marts: Large-scale data repositories, optimized for analytical processing and business intelligence.
    • Online Analytical Processing Queries (OLAP): Designed for multidimensional analysis of data.
    • Business Intelligence: Tools and techniques for extracting insights and trends from business data.

    Internet Features

    • Originated in 1960 as ARPANET, funded by the US Department of Defense's Advanced Research Projects Agency (DARPA).
    • A collection of interconnected networks with key features:
      • Data Centric: Focus on data transmission and processing.
      • Separation of Communication and Data Processing: Enables efficient data handling across different devices.
      • Packet Switching: Data is broken down into packets for transmission over the network.

    Packet Switched Network Features

    • Consists of two types of nodes:
      • Hosts: Originators and destinations of data packets.
      • Routers: Responsible for routing packets between hosts.
    • Connectionless System: No fixed routing scheme between hosts, providing flexibility and resilience.
    • "Best-effort" Delivery Network: Packets might be discarded due to congestion or link failures. Hosts are responsible for detecting and addressing these issues.

    Connecting to the Internet

    • Requires connecting a computer to an Internet-connected router.
    • Routers are maintained by universities, research centers, or commercial companies (ISPs).

    Internet Service Providers (ISPs)

    • Local ISPs: Lease connections from National or Regional ISPs and provide dial-up access to users.
    • National or Regional ISPs: Maintain their own backbone network and provide services to local ISPs.

    Domain Name System (DNS)

    • Converts domain names into human-readable IP addresses.
    • A distributed database system storing domain name information.

    How DNS Works

    • Client enters a domain name into the browser.
    • The browser contacts the client's ISP to obtain the IP address.
    • The ISP first checks its local cache for the address.
    • If the answer is not found, the ISP queries the domain's nameservers.
    • If nameservers are unknown, the ISP queries the root servers for the domain.

    Obtaining a Domain Name

    • The Internet Corporation for Assigned Names and Numbers (ICANN) manages IP address space allocation, protocol parameter assignment, domain name system, and root server management.

    Uniform Resource Locator (URL)

    Standard Organizations

    • International Organization for Standardization (ISO): Sets global standards.
    • Internet Advisory Board (IAB): Provides guidance and oversight for internet development.
    • Institute of Electrical and Electronics Engineers (IEEE): Sets standards in electrical and electronic fields, including networking.

    ISO-OSI Model

    • A reference model for computer networks, dividing networking functions into seven layers.
    • Provides standardization, promotes flexibility, and isolates functionality between layers.

    Why Use the ISO-OSI Model

    • Originally intended for standardizing computer networking protocols internationally.
    • Employs a "divide and conquer" approach by separating related functions into different layers.
    • Each layer is shielded from addressing details used by lower layers.
    • Facilitates design, comparison, and development of networking protocols.

    TCP/IP Layered Model

    • A model for internet protocols consisting of four layers:
      • Application Layer: Provides specific application services.
      • Transport Layer: Provides end-to-end transport service between hosts.
      • Network Layer: Forwards packets across the network.
      • Link Layer: Provides interface or access to the network.

    TCP/IP and OSI Model in Context

    • Example of how TCP/IP protocols map to the OSI Model:
      • Application Layer: FTP, HTTP, Telnet, SMTP (correspond to OSI Application Layer).
      • Transport Layer: TCP and UDP (correspond to OSI Transport Layer).
      • Network Layer: IP and ARP (correspond to OSI Network Layer).
      • Data Link Layer: LLC (Logical Link Control) and MAC (Medium Access Control) (correspond to OSI Data Link Layer).
      • Physical Layer: Provides the actual physical interface for data transmission (corresponds to OSI Physical Layer).

    Packet Transfer Steps

    • Host A:*
    • Application Layer: Generates data.
    • TCP Layer: Adds TCP header information.
    • IP Layer: Encapsulates data with IP header.
    • Link Layer: Encapsulates data with link layer frame header.
    • Network:*
    • Packet travels through network infrastructure.
    • Host B:*
    • Link Layer: Removes link layer header.
    • IP Layer: Removes IP header.
    • TCP Layer: Removes TCP header.
    • Application Layer: Receives final data.
    • Provides network access.
    • Handles physical network characteristics.
    • Manages access control protocols for different network standards.
    • Functions:
      • Encapsulating IP datagrams into frames.
      • Mapping IP addresses to physical addresses used by the network.

    Network Layer

    • Internet Protocol (IP):
      • Defines datagram format.
      • Establishes internet addressing scheme.
      • Moves data between Network and Transport layers.
      • Routes datagrams.
      • Handles fragmentation and reassembly of datagrams.

    IP Addresses

    • IPv4: 32-bit addresses.
    • IPv6: 128-bit addresses.

    IP Header Format

    • Structure:
      • Version: Indicates IP version (e.g., 4 or 6).
      • Header Length: Specifies header length.
      • Type of Service(TOS): Defines priority and traffic optimization parameters.
      • Total Length: Represents the total length of the datagram.
      • Identification: Allows fragmented packets to be reassembled.
      • Flags: Controls packet fragmenting behavior.
      • Fragment Offset: Indicates the position of a fragment within the original datagram.
      • Time To Live (TTL): Decrements with each hop to prevent datagram looping.
      • Protocol: Specifies the protocol being carried (e.g., TCP or UDP).
      • Header Checksum: Validates header integrity.
      • Source Address: IP address of the sender.
      • Destination Address: IP address of the recipient.
      • Options: Provides additional routing information and padding.

    Representing IP Addresses

    • Dot Decimal Format:
      • Example: 128.0.0.1
    • Binary Equivalent: Represents each decimal value as a binary number.
      • Example: 10000000.00000000.00000000.00000001
    • Structure:
      • Network Number: Identifies the network.
      • Host Number: Identifies a specific host within the network.

    Transport Layer

    • Provides communication services between applications on different hosts.
    • Two main protocols:
      • Transmission Control Protocol (TCP):
        • Connection-oriented protocol.
        • Handshaking ensures reliable data transmission.
        • Establishes connections between applications using ports.
        • Employs sequence numbers and acknowledgments for data reliability.
      • User Datagram Protocol (UDP):
        • Connectionless protocol.
        • Offers faster communication but does not guarantee data delivery.
        • Utilizes ports for addressing applications.

    Operating System

    • Collection of programs designed to manage system resources:
      • Memory: Allocates and manages memory usage.
      • Processors: Schedules and runs processes.
      • Devices: Controls and manages hardware devices.
      • Information: Organizes and manages programs and data.
    • The OS acts as a resource manager, allocating and reclaiming resources based on process needs.

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    Description

    This quiz covers the essential characteristics and performance metrics of web servers, including throughput and latency. It also discusses dynamic load balancing techniques that optimize traffic distribution across servers. Enhance your understanding of application servers and their role in web architecture.

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