IT3010 Lecture 03: Network Servers and Architecture
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Questions and Answers

In DNS design, what is a zone?

  • A single domain name mapping to multiple IP addresses
  • A list of names stored by the authoritative name server
  • A section of the name space that is contiguous (correct)
  • A domain name that does not map to any IP address

    • What type of mapping occurs when multiple domain names map to the same IP address in DNS?

  • Multiple domain names mapping to the same IP address (correct)
  • 1-1 mapping
  • Multiple domain names mapping to multiple IP addresses
  • Single domain name mapping to multiple IP addresses

    • How are secondary/redundant name servers typically updated in DNS design?

  • Through bulk transfer of configurations via TCP (correct)
  • By delegating subzones to other zones
  • Automatically by the authoritative name server
  • Manually by the primary/master name server

    • What is the main role of a server in a client-server architecture?

    <p>Offering services to clients</p> Signup and view all the answers

    In a client-server model, what is the main purpose of a client process?

    <p>Requesting services from servers</p> Signup and view all the answers

    What characterizes the creation of zones in DNS design?

    <p>Involves delegation from the owner node</p> Signup and view all the answers

    What does DNS stand for in the context of network design and management?

    <p>Domain Name System</p> Signup and view all the answers

    What is the purpose of a zone transfer in DNS?

    <p>To ensure reliability by transferring configuration data between servers</p> Signup and view all the answers

    Which protocol is responsible for dynamically assigning IP addresses to devices on a network?

    <p>DHCP (Dynamic Host Configuration Protocol)</p> Signup and view all the answers

    Where is the list of names that end with the same suffix stored in DNS hierarchy?

    <p>Each node in the hierarchy</p> Signup and view all the answers

    What is the primary function of a web server in a networked environment?

    <p>Managing shareable resources</p> Signup and view all the answers

    What is the defining characteristic of the client-server model for developing network applications?

    <p>Asymmetric roles of client and server processes</p> Signup and view all the answers

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

    <p>Translating humanly-meaningful names to numeric identifiers</p> Signup and view all the answers

    What is the role of a name server?

    <p>Translating text-based identifiers to numeric identification</p> Signup and view all the answers

    What does a naming scheme aim to achieve on a network?

    <p>Identify entities across the network uniquely</p> Signup and view all the answers

    According to RFC 781, what does the Domain Name System maintain?

    <p>The domain name hierarchy and translation services between it and address spaces</p> Signup and view all the answers

    What does a domain name (URL) uniquely identify?

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

    Why would one use a domain name (URL) instead of an IP address?

    <p>Easier for users to remember and type</p> Signup and view all the answers

    What is the purpose of the 'Flags' field in a DNS header?

    <p>To mark whether the message is a query or a response</p> Signup and view all the answers

    In a DNS message, what does the 'Additional RRs' field typically contain?

    <p>Resource records providing additional information</p> Signup and view all the answers

    What is the purpose of the 'Type' field in a DNS record?

    <p>To define the value associated with the record</p> Signup and view all the answers

    Which field in a DNS record specifies the Time-to-Live (TTL) value?

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

    Why are DNS negative queries cached?

    <p>To avoid repeating past mistakes like misspellings or incorrect search strings</p> Signup and view all the answers

    Which type of DNS record typically associates a domain with a mail server?

    <p><strong>MX</strong></p> Signup and view all the answers

    What is the purpose of caching DNS responses?

    <p>To provide quick response for repeated translations</p> Signup and view all the answers

    How is the lifetime (TTL) of cached data controlled?

    <p>By the owner of the data</p> Signup and view all the answers

    What does the 'Class' field represent in a DNS record?

    <p>The class of records being used, such as Internet (IN)</p> Signup and view all the answers

    How does Dynamic Host Configuration Protocol (DHCP) contribute to networking?

    <p>By dynamically distributing network configuration parameters</p> Signup and view all the answers

    Why do DNS servers use UDP for queries instead of TCP?

    <p>To allow for exponential backoff when retrying servers</p> Signup and view all the answers

    What happens if at least one replica of a DNS server is up?

    <p>Name service is available</p> Signup and view all the answers

    Study Notes

    DNS and Caching

    • DNS responses are cached to provide quick responses for repeated translations.
    • Cached data periodically times out, with a lifetime (TTL) controlled by the owner of the data.
    • The TTL is passed with every record.

    DNS Reliability

    • DNS servers are replicated to ensure name service availability even if one or more replicas are down.
    • Queries can be load balanced between replicas.
    • UDP is used for queries, with exponential backoff when retrying the same server.
    • The same identifier is used for all queries, ensuring that it doesn't matter which server responds.

    Dynamic Host Configuration Protocol (DHCP)

    • DHCP is a standardized networking protocol used for dynamically distributing network configuration parameters.
    • It provides IP addresses for interfaces and services.

    Properties of DNS Host Entries

    • Different kinds of mappings are possible, including 1-1 mapping between domain name and IP address, multiple domain names to the same IP address, and single domain name to multiple IP addresses.
    • Some valid domain names don't map to any IP address.

    DNS Design: Hierarchy and Zone Definitions

    • Each node in the hierarchy stores a list of names that end with the same suffix.
    • A zone is a contiguous section of the name space, with an associated set of name servers.
    • Zones are created by convincing owner nodes to create or delegate a subzone.

    DNS Design: cont…

    • Records within a zone are stored in multiple redundant name servers.
    • Primary/master name servers are updated manually, while secondary/redundant servers are updated by zone transfer of the name space.
    • Zone transfer is a bulk transfer of the "configuration" of a DNS server, using TCP to ensure reliability.

    Client-Server Architecture

    • Client-server architecture is the dominant model for developing network applications.
    • A server is a process that offers a service, while a client is a process that requests the service.
    • The server waits for requests from clients, and roles of the client and server processes are asymmetric.

    Domain Name System (DNS)

    • DNS is a hierarchical distributed naming system for computers, services, or any resource connected to the Internet or a private network.
    • It translates a humanly-meaningful, text-based identifier to a system-internal, often numeric identification or addressing component.

    Name Server

    • A name server is a computer hardware or software server that implements a network service for providing responses to queries against a directory service.
    • It translates an often humanly-meaningful, text-based identifier to a system-internal, often numeric identification or addressing component.

    DNS Message Format

    • DNS messages consist of 12 bytes, including name, type fields for a query, and RRs in response to the query.
    • Records for authoritative servers, additional "helpful info", and other information are also included.

    DNS Header Fields

    • Identification is used to match up requests and responses.
    • Flags are used to mark the query or response, indicate authoritative or non-authoritative responses, and support recursive resolution.

    DNS Record RR Format

    • Resource records (RRs) are tuples containing class, name, value, type, and TTL.
    • Classes include Internet (IN), Chaosnet (CH), etc., and each class defines a value associated with the type.
    • For the "IN" class, types include A, CNAME, NS, and MX.

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    Description

    This quiz covers the topics discussed in IT3010 lecture 03 by Shashika Lokuliyana, focusing on aspects such as Client-Server Architecture, Domain Name System (DNS), Dynamic Host Configuration Protocol (DHCP), Audit, Network Mapping, and Baselining. Explore the concepts related to networked applications, connecting computers over the internet, and data transmission.

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