Scott: Thanks a lot. It's very useful information. Actually I didn't know
how the whole process worked.
Bye
Luis Arango
----- Original Message -----
From: "R. Scott Perry" <[EMAIL PROTECTED]>
To: <[EMAIL PROTECTED]>
Sent: Friday, August 17, 2001 8:19 AM
Subject: Re: [IMail Forum] DNS records
>
> >Wait between 16 and 24 hours for the new DNS information to properly
> >propagate around the world, so if you sent an email to @jcws.net it
> >recognizes the new MX information.
>
> Just one quick note about DNS propagation. It can take anywhere from 0
> seconds to many years to DNS changes to propagate. In almost all cases,
> some servers will immediately query your DNS server for the change, while
> others will take up to [X seconds].
>
> "Propogation" is a misleading term. It makes it sound as though when you
> make a change, it goes to other servers, and they send it on to other
> servers, and so forth (kind of like how Usenet messages get spread). It
> doesn't work that way, though.
>
> When you make a change to your DNS server, there are probably lots of
> servers out there that have recently (within [x seconds]) queried your DNS
> server for information. For example, they may ask your DNS server for the
> MX record for your domain. Your server will respond with the MX record,
> and a "TTL" ("Time To Live") value of [x seconds]. You can set this to be
> whatever you want. Servers will then cache the information for those [x
> seconds]. If they need to know what your MX record is, and those [x
> seconds] haven't elapsed yet, the server will use what it was given before
> (since you told them it was OK to hold on to the information for [x
seconds]).
>
> So, assume that your TTL is 3600 seconds (and you didn't have any longer
> TTLs that could still apply; if you used to have a TTL of 1 month and
> changed it 2 weeks ago, you'll still have cached info on DNS servers). In
> that case, if you make a change to your DNS, "propagation" will take no
> more than 1 hour. On the other hand, if your TTL was set to 1209600
> seconds, it will take up to a week for the information to propagate.
>
> A couple things I haven't pointed out:
>
> o Different records can have different TTL values, which can confuse
> things; fortunately, most people use the same
> TTL for all the records on their domain.
>
> o If you change DNS servers (which requires a change at root), it could
> take up to about 72 hours for the change to
> take effect (typically up to 24 hours for the root servers to make the
> change, and up to 48 hours for the cached data
> to become stale)
>
> o Once you have made a change to your DNS, there is no easy way to find
out
> what your old TTL value was if you
> changed it. If you don't know completely what you are doing, you
> could have a 2 week TTL and change it to
> 1 day. That's good, but if you don't remember that the old TTL was 2
> weeks, you'll never be sure that everyone
> knows about the change.
>
>
> -Scott
> ---
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>
>
>
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