Domain Name Resolution Joshua Erdman Digital-Foundation.net
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 22.214.171.124 Web Server 126.96.36.199 Internet ISP DNS 188.8.131.52 End User PC GTLD Servers
Domain Name Table
GTLD History Internic ICANN Internet Consortium for Assigned Names and Numbers Domain Registrars Godaddy.com Register.com Net Sol
Features (e-mail, web hosting, advertising, etc.)
Easier to register domains
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 184.108.40.206.in-addr.arpa Business DNS 220.127.116.11 Web Server 18.104.22.168 ISP DNS 22.214.171.124 GTLD Servers