Every domain undergoes this "DNS propagation delay" during the initial stages of it's set up or when hosting server changes.
Normally you come up with this issue, when you have recently registered your domain name or changed hosting provider, payed for web hosting account and trying to connect to your site with browser or ftp to upload files. You try your domain on your web browser, you can't get your web page. Why? Tried to access your site's ftp server, but not able to. Why? This case is normally discussed as DNS propagation delay. So let us learn what is DNS propagation delay?
When you register your domain, the domain registrar (the company which registered your domain) will point your domain name to your web host DNS server. Then when you set up your website with your hosting provider, they create the Master DNS record in their Domain Name Servers for your domain.
When you try to access your website from your browser, it first needs to know the DNS authority for the domain. Then you will be redirected to visit your hosting provider's DNS server and finds the IP address for your domain name. Finally you will visit your website.
Why propagation delay occures and causes inaccessibility of website ?
To speed up the internet, your local Internet Service Provider (ISP) caches the DNS records queried through their server. They create their own copy of the master record, and access it locally to search for website, each time someone tries to view it. This procedure speeds up the internet, reduces the traffic to the master servers and thus help ISPwork faster. Each ISP caches DNS record and update it every few days. Each ISP have there own standard time frame to update the cache DNS record. This delay from your ISP will prevent you from viewing your website. This process is know as DNS propagation delay. The slow updating of the server cache is called propagation. The DNS information for your domain gets propagated across all server's on the web. After this propagation complete's your website will be accessible to all. Normally the DNS propagation time may take 24 to 72 hours to be in effect.
DNS propagation delay caused by doing domain registration with one company and hosting service taken from another company.
During the registration of a new domain name you have the option of setting your domain name's master DNS servers which should be the master dns servers of your web host. Many people won't do this setting and they keep dafault-parking page name servers provided by registrar. Parking page is meant for people who don't intend to host their domain with a website. When the first time, mostly just after registration, someone queries the domain name through browser or some other means, initiates a query from local ISP server to the present master server (default-parking-page), which results in showing default-parking page instead of intended website. During this first query your local ISP's DNS server caches your domain name's present Master DNS data and keep it till the next cache update time. Just after registration and check up of domain is working or not, people go for purchasing web hosting space from a different company. After the purchase of web space they have to update the new master dns server given by the hosting company in the domain name control panel with registrar. This updated information will not be passed for queries related to this domain till the next dns cahe update by the ISP DNS server. During this time nobody who uses this ISP will be able to browse the actual new web site and hosting space provided by the hosting company, instead of that they will get parking page.
DNS Propagation delay problem during change of hosting company
DNS propagation delay is involved in when you change web host. When you change hosting company you need to change the master dns server for your domain name. This new name servers will be found by ISP DNS servers only on the next dns cache update. Some ISPs take days to update cache. So during this time site will be inaccessible through that ISP.
First you need to try clearing Browser cache and DNS cache of your system. To clear browser cache (history) check the browsers help. After clearing browser cache close the browser. To clear DNS cache, in Windows XP and most of other windows versions, open a command prompt. Type the command ipconfig /flushdns and press enter. This will clear DNS cache. After clearing DNS cache open the browser and try to browse your domain name again.
When the above method doesn't solve your problem, you need to wait till the DNS cache update of your ISP. Usually 24 - 72 hrs. You have another option, to use a frequently updating DNS service. OpenDNS service is one of the fastest and intelligent DNS service which is free to use. You can setup OpenDNS servers as your system's DNS server, gives you faster result than your ISP Server. To know more about OpenDNS visit their web site www.opendns.com. Following are their Servers.
Preferred DNS Server : 18.104.22.168
Alternate DNS Server : 22.214.171.124
You can setup these DNS servers in your PCs TCP/IP settings, DSL Router etc. To see how to set it up for your Computer, Router or Server click here. Most of the time this solves inaccessibility of web site due to DNS propagation delay.