Re: Ranting on ipcache bogosity

From: Oskar Pearson <>
Date: Wed, 21 Aug 1996 12:51:35 +0200 (GMT)

Eric Wieling wrote:

(Hi Duane - Are we off on a tangent? Should I take a long hard look at the
source? Should I just bugger off? ;)

I have removed the general mailing list from this to keep the friends that
I have ;) Maybe we need a "developers" list and an announce list -
If I were only interested in announcements, I would have unsubscribed
a while ago...

Basically the main question is as follows:
When squid connects, and downloads a page, and saves it to a directory,
does it index the directories by URL or by IP?

> The Netscape way of load blanacing would be a problem. However, the
> only problem I can see with the "correct" way of doing things is
> making sure that Squid stores the host name associated with the oject
> is actually a host name, rather than an IP address. Of course, that
> would require additional DNS lookups at various places.
Hmm - There shouldn't be a problem with this, assuming that:
They have set up squid so that it will talk to a local DNS server
to resolve names.
That DNS server is set up to recurse - so that it will cache the
actual returned values, not refer it to a remote server.

My thinking is that (we for example) do most of our access through
a satellite link, which increases send/ack times substantially,
and each DNS lookup that refers to a machine as squid's major DNS,
would have a large turnaround time. On a slow link, this could
be up to 2 seconds - 2 seconds before the cache even returns an answer...
(No, that's not how long our lookups take! ;)

(This is why all of our access lists are based on IP addresses, not on
domain name, especially since so many IP's don't have reverse addresses!


> Some time ago Oskar Pearson said:
> > What about the following too:
> >
> > When multiple dns entries are returned, cache them all identically,
> > my reasoning is as follows - when the new version of Netscape came out,
> > they had a random load balancing system to keep their servers sane.
> >
> > BUT - they had about 20 servers, so, while one of our users downloaded
> > netscape from ftp1, 19 other people were downloading it from the
> > other servers... This problem can only get worse :(
> >
> > Fixing this is going to be hard to implement because:
> > Netscape does it's load balancing in a strange way: they set a very
> > low TTL on their records, and then rotate their records on their
> > name server. (ie - if you find out the address for now,
> > it may give you two records, but if you do it five minutes later, you
> > will get a different address...
> >
> > You could (I suppose) get it to cache all DNS requests for something like
> > 24 hours :) (Evil grin ;) and only re-lookup if you issue a reload command.
> >
> > (Yes I know that there are all sorts of bad points about not following
> > RFC's reguarding DNS lookups etc, but please don't flame me!)
> >
> > On the other hand, something like works on a much
> > easier system to cache:
> > When you ask for, it returns 16 different IP addresses...
> >
> > It seems that squid would store the files with an algorithm based on
> > the IP address?
> [snip]
> --
> Eric Wieling
> Advanced Network Research
> InterCommerce Corporation
> Pager: 800-758-3680
> The world needs no help seeing a fool for what they are.
Received on Wed Aug 21 1996 - 03:53:38 MDT

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