 |  |
On 07/10/00 at 16:07, Higher Powered web wrote:
Re: DNS not propogating properly??
From: Global Homes Webmaster
Date: Monday, July 10, 2000
Time: 5:18:01 pm
> Hmmm...
>
> well I guess I have to do it. this sucks, because i'm changing isp's next
> month and will have to do it all over again!!
>
> Here's a question:
> When I do a traceroute on any site on my server, the last hop goes to
> 208.1.125.162(good) but there is no name listed- every other site I checked
> has a server name listed here.
> Why is that, and is that not a problem?
It's because there's no PTR (reverse) record for 162.125.1.208.in-addr.arpa.
Traceroute attempts to do a reverse look-up for each hop's IP, so that it can
tell you the canonical names. If there's no PTR, traceroute shrugs and moves
on. Not having PTRs is generally not a problem unless you're using a protocol,
like IRC or SMTP, that uses reverse look-ups to match your forward and reverse
info as a (crude) security check.
> also, once I change the ip addresses, will I loos all traffic?
> I've never quite understood this part. I know about the cached servers(and
> AOL's lovely caching process) but when the request actually comes to my DNS,
> is it in the form of an ip or a name. If it's a name, then I'm safe,
> correct?
> If it's an ip, there will be no records in my DNS and it will fail, correct?
If you just summarily change the IP addresses in your DNS entries without
preparing for it, then yes, you will probably lose some traffic for at least
the TTLs of the changed records. A common strategy for making this kind of
change is to first change the TTLs[1] and refresh[1] values for the affected
records to something fairly short, then wait for the length of the old
TTL/refresh before making your IP address changes. That way, the longest any
other server should hold onto the old data will be the shortened refresh plus
the shortened TTL. Once your changes have been made, you can change the TTLs
back to their 'normal' values. As an example, suppose your TTLs are 86400
seconds (1 day):
1. Change your TTLs and refresh values to, say, 300 seconds (5 minutes).
2. Wait 24 hours (or the old refresh value, whichever is longer) for any
cached records out in the wide world of the 'net to expire and for your
secondaries to pick up the shortened TTL/refresh values.
3. Change your A records.
4. Change your TTLs and refresh values back to their normal values and you're
done.
The longest anyone should be unable to reach the machines with new IPs is 10
minutes (the shortened TTL plus the shortened refresh -- that would be the
case if both a secondary did a zone transfer and some other name server cached
a record immediately before the change occurs).
You can also do the above by shortening the refresh in two steps, since it's
typically longer than the TTLs. So, you might shorten the refresh to 24 hours
(the TTL value), wait the length of the old refresh, shorten both refresh and
TTLs to 5 minutes (or whatever), wait 24 hrs, make your changes, and, finally,
set TTLs and refreshes back to normal values.
> Thanks a million for the help!
No worries -- just making a deposit in the karma-bank... 8^)
[1] 'TTL' (Time To Live) is the maximum time non-authoritative servers are
allowed to cache records. 'Refresh' is the maximum time secondary servers can
wait before checking a master (primary) server for changes in a zone.
Christopher Bort
Messages In This Thread:
Return to Digital Point Solutions' Home Page
| home | |
| products | |
| services | |
| support | |
| email lists |
| optigold isp | |
| optigold isp news | |
| home inspection | |
| inspectrix | |
| java companion | |
| oracle | |
| quickdns pro | |
| search engine | |
| veterinary |
| tips | |
| employees | |
| free tools | |
| portfolio | |
| jobs | |
| contact |
888/4-DPOINTSupport:
858/452-3696