You?ve registered your domain name, and paid for hosting with a hosting provider, and uploaded your website to the web server. If this is all done, why can?t you see the results of your hard work right away? What is this DNS propagation people keep telling you about?
In order to understand DNS propagation, you must first understand a little about
how DNS works. When you set up your website with your hosting provider, they create
a Master DNS record in their Domain Name Servers. Your domain registrar (the company
you paid for the honor of owning your domain name) points to your web host?s DNS
server as being the master authority of your domain.
When any outside source wants to know how to find your website, they first go
to the registration database to find out who the DNS authority is for your website.
Then they visit your hosting provider?s DNS servers to find out what the IP Address
is for your domain name, and from there your audience can now view your website.
The problem with this whole scheme is that in order to speed up the rate at which
their customers can view the internet, each Internet Server Provider caches their
DNS records. This means that they make their own copy of the master records, and
read from them locally instead of looking them up on the Internet each time someone
wants view a website. This actually speeds up web surfing quite a bit, by (1)
speeding up the return time it takes for a web browser to request a domain lookup
and get an answer, and (2) actually reducing the amount of traffic on the web
therefore giving it the ability to work faster.
The downside to this caching scenario and what makes it take so long for your
website to be visible to everyone, is that each company or ISP that caches DNS
records only updates them every few days. This is not any kind of standard, and
they can set this time anywhere from a few hours to several days. The slow updating
of the servers cache is called propagation, since your websites DNS information
is now being propagated across all DNS servers on the web. When this is finally
complete, everyone can now visit your new website. Being that the cache time is
different for all servers, as mentioned above, it can take anywhere from 36 to
72 hours for DNS changes to be totally in effect.
A great domain registrar is AUSWEB Domain Names