Re: [AMBER-Developers] Amber web server problems

From: Ross Walker <ross.rosswalker.co.uk>
Date: Wed, 15 Jun 2011 09:44:53 -0700

Hi Dave

> Note that "dscacheutil -flushcache" (the suggestion on several web
> sites)
> doesn't get me back to a correct Amber web page.
>
> Let me know if you want any changes at the Rutgers end, e.g. to make
> ambermd.rutgers.edu point to the correct pages. Or, you might consider
> using
> git to update the backup copy at SDSC.

No this just flushes your local cache on your machine. It does not flush the
cache on your actual DNS server that you have no control over. Our time to
live on the DNS entry for ambermd.org is 24 hours so the most it can take is
24 hours. You can do:

dig x ambermd.org

and you'll get among other stuff:

;; ANSWER SECTION:
ambermd.org. 40977 IN A 192.31.21.165

Where the 40977 is the time to live (on your DNS server) in seconds. once
this ticks down to zero it will refetch from the master DNS server
(ns3.ukdnsservers.co.uk) for the domain and all should be good.

For the moment I just updated the back with the git contents so at least the
page is up to date. It looks like the alias only vanished in the last few
hours so this doesn't affect everybody. Adrian for example goes to the
Rutgers IP.

>Other questions, reflecting my ignorance about DNS and web servers:

>1. "128.6.69.24" (above) gets to my personal web page, not the amber one.
>How does ambermd.org actually know which web pages to point to on our
server?

The server works off the incoming referral URL used in the browser. This is
how you can server multiple pages off of a single IP address. There will be
a default for the ipadress that you get if the URL used by the user does not
match any of the templates in the httpd.conf file. Hence why it goes to your
home page.

>2. Is there a way to manually flush the DNS cache, and/or otherwise check
>that things are now working?

Only by having root on your DNS server itself. :-(

We should be good for the moment though since it should be fairly
transparent now I updated the backup.

All the best
Ross

/\
\/
|\oss Walker

---------------------------------------------------------
| Assistant Research Professor |
| San Diego Supercomputer Center |
| Adjunct Assistant Professor |
| Dept. of Chemistry and Biochemistry |
| University of California San Diego |
| NVIDIA Fellow |
| http://www.rosswalker.co.uk | http://www.wmd-lab.org/ |
| Tel: +1 858 822 0854 | EMail:- ross.rosswalker.co.uk |
---------------------------------------------------------

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Received on Wed Jun 15 2011 - 10:00:03 PDT
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