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DNS
and how it
effects our domain
Part - 2
The 3 to 4 day propagation period - Understanding what happens during
this time frame:
In short, patience is a virtue. Remember what we talked about earlier regarding
the shear size and scope of the worlds DNS system? In short, when you change
your DNS settings, these new settings must propagate throughout the worlds DNS
servers. It also means that every ISP (Internet Service Provider), must update
their DNS records to reflect these new changes, which in most cases, is done
automatically every 24 hours, but not always however...
Where do the Root Name Servers receive their information from?
The Root Name Servers will query "domain registers" several times a day. Domain
Registers, being entities such as Network Solutions, and the newer OPEN SRS
based systems. The Root Name Servers will gather this information from the many
registers now in existence, and update their master records accordingly. Now
your ISP must access the Root Name Servers, and update their DNS records, which
reside on their 'local' DNS server. This process is fully automated and most
ISP's will check the Root Name Servers for updates every 24-hours. Beware
however, that some lame ISP's will delay this process for as much as 2 to 4 days
in some cases. If that happens, it will no doubt cause additional confusion, as
everyone else will be reaching your new account on our servers except you. This
is because your current ISP has not updated their DNS records, and or have not
cleared their DNS cache, which means they'll still be pointing your domain name
to your old server. If it's a new domain name you've registered, then you'll
receive a blank "Site Not Found Page."
The DNS propagation process is not limited to ISP's!
HA.. Just when you thought you had it all figured out! Unfortunately, there's
more folks. The Internet itself must update/clear its DNS cache as well. When we
say the Internet, we mean the numerous intermediate "points of access" you're
routed through before reaching your final destination. For the most part, these
intermediate points of access consist of "Internet Routers" and "Internet
Caching Engines." These too, maintain their own DNS cache, which assists them in
routing traffic/resolving URL's to the correct destination IP's. Don't worry
though, as Internet routers are usually faster at clearing their DNS cache than
ISP's are.
What to expect during this 2 to 4 day propagation period:
In most cases, the propagation process will take at least 48 hours to complete.
The first thing that happens is the "World Root Name Servers" will check all of
the various "Domain Registers for updates. Ok, so now the Root Name Servers have
done their job. The rest of it is up to the many ISP providers who "should be"
updating their DNS records (at least every 24 hours), but a number of them will
not.
Side effects that can be expected
during the propagation time frame:
It's perfectly normal for strange things to happen within the 48-hour
propagation period, but sometimes longer. While we could provide a full list of
all the anomalies that can occur during the DNS propagation period, we'll stick
to some of the most common scenarios that most people experience:
HELP! My friends can reach my new site,
but I'm still being directed to the OLD ONE!
This is a class case of your friends ISP (who did update their DNS records), but
yours unfortunately did not. As a result, your ISP is still pointing your domain
name to the old DNS record, which is your old hosting account. Wait a couple of
more days, and if it appears that everyone but you can access your new account,
then contact your ISP and tell them to expire their old DNS cache records.
WOW! http://www.mydomain.com was taking
me to my new Broadview Networks account just a minute ago, but when I try it
now, I'm being taken back to my old hosting account - what's up with this?
In all likelihood, your ISP may be in the
process of clearing their DNS cache, and or updating their local DNS server
records. During this small interval, it's normal to fluctuate between the new
and old web site, as the old DNS records may not have completely expired from
their cache yet. Give it another several hours and it should be fine.
HEY! My new site comes up for me, but
my friends are being directed to my old one!
Break out the coffee and donuts, and
consider yourself lucky. Your ISP is on the ball and updates DNS records/ clears
DNS cache in short regular intervals. Your friends may be using an ISP, which is
not as fast, and or efficient at doing so. The only remedy for this is time.
Eventually, the other ISP's DNS cache will expire and be replaced with the
updated DNS records.
What's going on with my email? When I
try to access it, I receive a "host does not exist" or a "cannot authenticate"
error message.
This can happen for a number of reasons, but in most cases, it's because your
new DNS records have not fully completed the propagation process yet.
Consequently, you may be trying to access your old email account on your "old
server", which you may have already cancelled, or it's in a state of DNS flux,
which means it points to the new server one moment, and the next, points back to
the old server.
Give it some more time and it will eventually settle down. In the meantime,
consider accessing email from your account using the WebMail based reader.
Checking your DNS update
status (outside of your ISP):
In the event you're becoming impatient, and or are wondering if the rest of the
world outside of your ISP can access your new site, you can proxy yourself to
another network and test it there. In many cases, you'll be surprised to see
your site responding perfectly, yet when you attempt it directly from your ISP's
servers, it does not exist.
There are several services, which allow anonymous surfing across the net. While
this is not the intent here, they can be used for trouble shooting domain
resolution problems. How? Because they proxy you through their network, which
means your URL requests are controlled by "their" DNS cache records. These
services update/expire their DNS cache far more often than ISP's, which makes
them well suited for testing your domain name through a network, which operates
with the latest DNS updates across the web.
To run this check, you can try accessing your site through one of these two
services:
http://www.opendns.com/cache/index.php
Both of them allow you to enter a URL, and
proxy your request through their servers. If your site is accessible from these
servers, then chances are, your ISP has yet to expire their old DNS cache
records.
DNS - Domain Name Server -
Part 2
Knowledgebase
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