Domain Name Resolution Joshua Erdman Digital-Foundation.net
DNS Background <ul><li>What is a domain name? </li></ul><ul><li>Familiar, easy to remember names for computers on the Inte...
DNS Background What does it mean to &quot;register&quot; a domain name? The Internet domain name system (DNS) consists of ...
So what is DNS Resolution? DNS Resolution is the procedure used to resolve a IP address from a domain name.   This is very...
DNS Resolution analogy <ul><li>Looking up a phone number </li></ul><ul><li>Get the phone book of the right city </li></ul>...
DNS Foundation All computers communicate by addressing each other using IP addresses.   So every time you try to connect t...
Domain Names vs. URLs A domain name is contained in a URL.  See the examples below.   ftp://ftp.company.com/downloads.repo...
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....
Domain Name Table
WHOIS DB
GTLD History Internic ICANN Internet Consortium for Assigned Names and Numbers Domain Registrars Godaddy.com Register.com ...
Registrars <ul><li>Benefits: </li></ul><ul><li>Price Wars </li></ul><ul><li>Features (e-mail, web hosting, advertising, et...
IP Address Registration ICANN Internet Consortium for Assigned Names and Numbers IP Registrars ARPNIC Asia Pacific Registr...
Reverse DNS Resolution Reverse DNS Resolution is the procedure used to resolve a domain name from an IP address.   Recall:...
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 ...
Reverse DNS Resolution <ul><li>How is Reverse DNS this useful? </li></ul><ul><li>Tracing traffic that goes through Firewal...
Questions & Answers
 
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DNS resolution

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DNS resolution

  1. 1. Domain Name Resolution Joshua Erdman Digital-Foundation.net
  2. 2. DNS Background <ul><li>What is a domain name? </li></ul><ul><li>Familiar, easy to remember names for computers on the Internet (such as internic.net). </li></ul><ul><li>Correspond to a series of numbers (called Internet Protocol numbers, AKA IP addresses) that serve as routing addresses on the Internet. </li></ul><ul><li>Domain names are used generally as a convenient way of locating information and reaching others on the Internet. </li></ul>
  3. 3. DNS Background What does it mean to &quot;register&quot; 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
  4. 4. 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.
  5. 5. DNS Resolution analogy <ul><li>Looking up a phone number </li></ul><ul><li>Get the phone book of the right city </li></ul><ul><li>People are listed by last name </li></ul><ul><li>Then narrow it down to a first name. </li></ul><ul><li>It is the phone number that allows you to communicate over the phone, not the person’s name. </li></ul>
  6. 6. 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.
  7. 7. 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)
  8. 8. 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
  9. 9. Domain Name Table
  10. 10. WHOIS DB
  11. 11. GTLD History Internic ICANN Internet Consortium for Assigned Names and Numbers Domain Registrars Godaddy.com Register.com Net Sol
  12. 12. Registrars <ul><li>Benefits: </li></ul><ul><li>Price Wars </li></ul><ul><li>Features (e-mail, web hosting, advertising, etc.) </li></ul><ul><li>Easier to register domains </li></ul><ul><li>Problems: </li></ul><ul><li>Long distance wars </li></ul><ul><li>ISPs using 1 registrar </li></ul><ul><li>Customers registering because it is now so simple </li></ul>Registrars Godaddy.com Register.com Net Sol
  13. 13. 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
  14. 14. 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.
  15. 15. 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
  16. 16. Reverse DNS Resolution <ul><li>How is Reverse DNS this useful? </li></ul><ul><li>Tracing traffic that goes through Firewalls </li></ul><ul><li>Documentation </li></ul><ul><li>E-mail server validation </li></ul>
  17. 17. Questions & Answers

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