Domain resolving to its website

[Dave_Z]

Hello everyone!

I just thought, for the benefit of everyone especially the newbies, that people should know how and why domain names take a long while to resolve to their websites and what not.

Some people might be wondering why it takes long; that despite the advances in technology, shouldn't things like that take effect soon after if not immediately?

So here's my questions so far:

1. If a domain name has expired for a couple of days, been deactivated because of that, and renewed, how come it takes about 24-48 hours before it resolves to its website?

2. Registrars normally tell people that it takes 48-72 hours for DNS propagation to take effect. Some people (especially webmasters), however, claim this can happen in actually 8 hours or so.

Which is which? What gives?

The reason I ask these is because it irks me whenever I try to explain to people the above 2 things, yet they get angry & insist I fix this as soon as possible or else.

As if it's always my fault such occurs....

 

[Whisper]

1. If a domain name has expired for a couple of days, been deactivated because of that, and renewed, how come it takes about 24-48 hours before it resolves to its website?

This happens because the root name servers (i.e. the main DNS servers that serve every domain in the 'Net) don't have a copy of the DNS datas (called "zone") for the domain deleted and it can only be restored from the previous one.
This, obviously, take some time because every ISP in the world should know the new address is still active, and not everyone sync with the root DNS the same time.

2. Registrars normally tell people that it takes 48-72 hours for DNS propagation to take effect. Some people (especially webmasters), however, claim this can happen in actually 8 hours or so.

Same as above, if you're so lucky to have a provider that updates its internal DNS cache every eight hours or so, you've got it! Registrars are used to tell such a long time because they should be sure that the domain is visible and active everywhere, since they're supposed to have customers all over the world.

My .2


Whisper

A quick addition:

Such those changes are not supposed to take immediate effects, since DNS datas are cached for a default time chosen by each ISP and by the root servers themselves. If you're into configuring DNS, you should have heard about TTL and those things: in fact, when your DNS are set, and your TTL is very low, your changes take (almost) immediate effect (i.e. when you create a subdomain, like yoursub.yourdomain.ext).

 

[Dave_Z]

Originally posted by Whisper
This happens because the root name servers (i.e. the main DNS servers that serve every domain in the 'Net) don't have a copy of the DNS datas (called "zone") for the domain deleted and it can only be restored from the previous one.
This, obviously, take some time because every ISP in the world should know the new address is still active, and not everyone sync with the root DNS the same time.

The previous one coming from where? The registrar?

Also, how long will it take for each root server to update among themselves, given they're 13 of 'em?

 

[Kodeking]

I like to think of the DNS thing as a census. New people constantly come into, and leave the country, but the Government doesn't want to calcualate the population every minute. So they only do it every few years.

Its kinda the same with local dns servers. They dont have the power or speed to update every 5 minutes, so they do it every few hours.

I would think however that the more popular isps would update more often, as they have more of a variety of people/interests + more income to pay for better technology.

 

[GTech]

One tip I can offer, when waiting to see if the DNS has resolved, is:

in a dos window, type:

ipconfig /flushdns

Then do a ping or tracert command to your domain to see if it's going to the right IP.

Not as experienced on the other end. Hope this helps.

 

[dawg]

I love this thread. DNS is very close to my heart. I teach a dns class at college and also work with it everyday at my job. Alot of good comments here and very true what was posted. Very good guy's you are realy smart.

Ever wanted to control your own dns servers? And zones? Here is a guy that will let you do just that take a look:

https://secure.xtremeweb.de/dns/

Cheers.

P.S. If you use his dns servers he does exept donations. Just a thought.

 

[g0ldy]

Wow you learn something new every day

Great replys

 

[Dave_Z]

Originally posted by Wade
One tip I can offer, when waiting to see if the DNS has resolved, is:

in a dos window, type:

ipconfig /flushdns

Then do a ping or tracert command to your domain to see if it's going to the right IP.

Not as experienced on the other end. Hope this helps.

Won't a ping compromise your computer's security, like the firewall, perhaps?

I instead use websites out there that do that instead of pinging using my computer itself.

So based on the information provided above, once the registrar forwards the DNS info to the appropriate registry after the domain has been renewed or the DNS changed, the actual waiting part is for all the world's ISPs to update their internal DNS cache?

 

[g0ldy]

Originally posted by davezan
Won't a ping compromise your computer's security, like the firewall, perhaps?

I instead use websites out there that do that instead of pinging using my computer itself.

Dont pings only tell if you lose data packets and how fast it gets back?

 

[Whisper]

Originally posted by g0ldy
Dont pings only tell if you lose data packets and how fast it gets back?

Yeah... almost, I guess so it is

Originally posted by davezan
The previous one coming from where? The registrar?

Also, how long will it take for each root server to update among themselves, given they're 13 of 'em?

When a registrar register a new domain, it's put into the root servers for the TLD you've chosen (.com/.net aren't handled by the same DNS roots as .org, e.g., don't confuse the 13 Internet roots with them), then delegated to the DNS servers you've chosen (your ISP / Hosting Provider ones).

When you request, with a ping, an HTTP/FTP/SMTP/POP3/whatever connection or something the IP address associated with your domain, your computer do the following:

1. They ask your ISP's DNS servers for the data, since it may be cached;
2. If it's cached, they retrieve it and stop; If it's not, they give referals to the root servers (each ISP choose which one to refer to, my ISP, e.g., keeps updated DNS datas for almost every TLD, but I know of others that refers to the 13 roots);
3. Your computer keeps asking and asking every DNS server it's refered, when finally he comes to the ones that host your domain (those listed in the WhoIs);
4. Your computer asks those servers, they give back to it the IP address and... you're done!

Also, the censum-like explanation by Kodeking is really really good, you've to think they simply can't update every few minutes because that would cause an high bandwidth use.

 

[Terry]

Great thread, thanks all!

 

[Dave_Z]

Originally posted by Whisper

Also, the censum-like explanation by Kodeking is really really good, you've to think they simply can't update every few minutes because that would cause an high bandwidth use.

Like being stuck in highway traffic on a Monday morning since everyone's going thru at the same time. :hehe:

 

[Whisper]

Originally posted by davezan
Like being stuck in highway traffic on a Monday morning since everyone's going thru at the same time. :hehe:

Yeah, it should be something like that :lol: