Domain Name System

Possible Scenarios You want a web site for your business You want to renovate your current web site You want to change your current web hosting to other company You want a couple of different domain names for the same web site

Terminology Domain Name Sub Domain Name (Host Name) mybusinessname.com, mybusinessname.net 기억하기 쉬운 이름 Sub Domain Name (Host Name) www.mybusinessname.com, email.mybusinessname.com Domain Name Registrar 도메인 네임 등록처 (등록 대행 회사) Godaddy, networksolutions Domain Name Registrant 도메인 네임 등록자 도메인 네임에 대한 한시적인 사용권을 가짐

도메인 네임 등록 절차 도메인 네임이 등록되어 있는지 체크 도메인 등록 회사 선택 도메인 네임 등록 Using whois lookup 도메인 등록 회사 선택 Domain name registration + web hosting Domain name only 도메인 네임 등록 유효기간: 1년 or more Top level domain (TLD): .com, .net, .biz, … Around $10.00 per domain for one-year

Whois record 특정 Domain name에 대한 각종 정보를 제공 Whois record lookup Domain name registrar Domain name registrant Expiration date Whois record lookup 어떤 도메인의 Whois record를 검색하는 것

Example of Whois lookup https://www.networksolutions.com/whois/index.jsp mylunchdelivery.com

Result of WHOIS lookup

IP Address 인터넷이 데이터 전송을 위해 사용하는 주소 4 Byte = 4개의 8bit 28 = 256개의 값: 00000000 (= 0) – 11111111 (= 255) Domain name should be hooked up with IP address to be shown to public www.kumranumc.org  76.123.29.210 10010011 11001001 01000111 11001010

IP Address Lookup www.kumranumc.org 72.210.45.109

Reverse Lookup www.kumranumc.org 72.210.45.109

IP Address Lookup nslookup: MS-DOS command for IP address (reverse) lookup

Name server 특정 도메인 네임에 대한 IP Address 를 포함한 도메인 관련 데이타를 가지고 있고 lookup Query에 대해 IP address나 도메인 네임 정보를 제공 이 데이타를 Domain Name Record라고 부름 Domain registrar company는 이 name server에 대한 데이타를 수정할 수 있는 기능을 제공 (through their websites)

[Godaddy domain manager]

Domain Name Records A Record CName MX(eMail eXchange) Record TXT/SPF IP address for a domain name @: domain name itself * : wild card (default host name) CName Alias Ex: iphone.radiokorea.com  @ MX(eMail eXchange) Record Record for email transfer TXT/SPF For email security Bulk emails sent from a site with no TXT/SPF record are likely to be rejected

Domain Name Forwarding Forwarding with masking Novaone.com/novaone.net Browser의 address bar의 주소는 다르지만 보여주는 html은 같은 것 Forwarding with no masking www.gogle.com  www.google.com Browser 의 address bar 의 주소가 수정된 즉 forwarding 된 주소를 보여줌

Domain Name Transfer Domain name transfer means changing your current domain name registrar to other company for your domain name Ex: network solution  godaddy It is done with no charge

Homework If you don’t have yet a domain name and want to launch online business, you will need a domain name. List up a couple of domain names and find out whether the domain names are already registered. Register one of the unregistered domain names on a domain name registrar company (e.g., godaddy.com)

Homework If you have your website and don’t know your domain name registrar, you need to find out the domain name registrar for your domain Find out your domain name registrar using whois lookup Try to login the domain name registrar company and find your domain record Do the next slide

Homework If you already know your domain name registrar and you can login the company to edit domain name record, practice the followings. Find out your domain name records as following A Record CName MX Record Register one of the frequently mistyped names for your domain name Check whether @ and * exist

Next class HTML 구조 CSS (Cascading Style Sheet) Major tags a, img, div, span, table DOM (Document Object Model) Javascript, jQuery Practice: a product page (상품 페이지) 작성