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DNS resolution
 

DNS resolution

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    DNS resolution DNS resolution Presentation Transcript

    • Domain Name Resolution Joshua Erdman Digital-Foundation.net
    • DNS Background
      • What is a domain name?
      • Familiar, easy to remember names for computers on the Internet (such as internic.net).
      • Correspond to a series of numbers (called Internet Protocol numbers, AKA IP addresses) that serve as routing addresses on the Internet.
      • Domain names are used generally as a convenient way of locating information and reaching others on the Internet.
    • DNS Background What does it mean to "register" a domain name? The Internet domain name system (DNS) consists of a directory, organized hierarchically, of all the domain names and their corresponding computers registered to particular companies and persons using the Internet. When you register a domain name, it will be associated with the computer on the Internet you designate during the period the registration is in effect. – Taken from ICANN.com
    • So what is DNS Resolution? DNS Resolution is the procedure used to resolve a IP address from a domain name.   This is very similar to how we get the phone number of a person we want to contact.   It is all based on hierarchy.
    • DNS Resolution analogy
      • Looking up a phone number
      • Get the phone book of the right city
      • People are listed by last name
      • Then narrow it down to a first name.
      • It is the phone number that allows you to communicate over the phone, not the person’s name.
    • DNS Foundation All computers communicate by addressing each other using IP addresses.   So every time you try to connect to a website, or send an e-mail, DNS resolution is occurring. Just like phone numbers, multiple domain names can resolve to the same IP address.
    • Domain Names vs. URLs A domain name is contained in a URL. See the examples below. ftp://ftp.company.com/downloads.report.doc http://www.networkclue.com/index. php Protocol Resource or File Hostname Domain Name Fully Qualified Domain Name (FQDN)
    • DNS Resolution Scenario 5 components http://www.google.com Business DNS 1.2.3.1 Web Server 1.2.3.4 Internet ISP DNS 3.3.3.1 End User PC GTLD Servers
    • Domain Name Table
    • WHOIS DB
    • GTLD History Internic ICANN Internet Consortium for Assigned Names and Numbers Domain Registrars Godaddy.com Register.com Net Sol
    • Registrars
      • Benefits:
      • Price Wars
      • Features (e-mail, web hosting, advertising, etc.)
      • Easier to register domains
      • Problems:
      • Long distance wars
      • ISPs using 1 registrar
      • Customers registering because it is now so simple
      Registrars Godaddy.com Register.com Net Sol
    • IP Address Registration ICANN Internet Consortium for Assigned Names and Numbers IP Registrars ARPNIC Asia Pacific Registry RIPE European Registry ARIN American Registry for Internet Numbers
    • Reverse DNS Resolution Reverse DNS Resolution is the procedure used to resolve a domain name from an IP address.   Recall: Multiple domain names can resolve to an IP address (just like multiple people can have the same phone number). It is the ISP’s responsibility to maintain reverse DNS tables.
    • Reverse DNS Resolution 4 components Internet 4.3.2.1.in-addr.arpa Business DNS 1.2.3.1 Web Server 1.2.3.4 ISP DNS 3.3.3.1 GTLD Servers
    • Reverse DNS Resolution
      • How is Reverse DNS this useful?
      • Tracing traffic that goes through Firewalls
      • Documentation
      • E-mail server validation
    • Questions & Answers
    •