DNS sloooooowwwww.....

Kezza · n00b Joined: 11 Dec 2002 Posts: 49

I'm a newbie to Linux and love Gentoo but am a little disappointed in Internet performance. I'm sure something is not configured correctly.

Using my dialup internet connection under Linux seems a lot more sluggish under Linux than under Windows on my PC (P4 2GHz, 768MB, Ext 56k modem on ttyS0). Under windows web-pages visibly begin to be loaded within 1s of typing in the URL; under Linux web-pages visibly begin to be loaded after 3-4s.

Ping times are as follows:

Linux:

slyzer · Tux's lil' helper Joined: 12 Oct 2002 Posts: 96

Hi,

that's a 'feature' of the Internet Exploder. There was an article at slashdot a while ago. IE ignores the TCP standard so he loads faster. Try to search at slashdot it was explained very good

cu
slyzer

474 · l33t Joined: 19 Apr 2002 Posts: 714

Two thoughts spring to mind:

1. Ensure that the modem is initialised with the same sequence of AT commands before the dial-up operation occurs. You can get this from the .inf file (which is the Windows driver), or by running something like portmon from http://www.sysinternals.com and sniffing the traffic to your serial port. These commands could affect performance

2. How are you specifying your DNS servers? Make sure you allow DHCP to choose them, because many ISPs have more than two DNS servers and assign different ones according to which dial-up pool you end up being a part of.

I believe also that Windows 2000 and higher use a client-side DNS resolver cache (as evidenced by the presence of the ipconfig /flushdns command). You may want to configure bind or djbdns as a cacheing-only nameserver for a fair comparison because, AFAIK, the Linux DNS resolver routines don't have this functionality by default. I have also found that sometimes (rarely, but sometimes) the core Internet root DNS servers perform better than those of one's ISP (this presently seems to be the case with my cable service). If you run a cacheing server, the proximity of the DNS server becomes slightly less important - particularly if you regularly visit the same sites or hosts.

Of course, there could be several other factors at play here but maybe the above will provide a lead.

EDIT: it occurred to me that as you used an IP address for your ping tests, DNS has little to do with it; at least not tests involving ICMP packets anyway.

474 · l33t Joined: 19 Apr 2002 Posts: 714

krt · Posted: Fri Feb 07, 2003 9:01 am Post subject:

as goofy as this sounds - compare the init strings Windows is sending to your modem and what init strings Linux is sending to them.. I'm willing to bet that Linux is sending out things for a generic setup, whereas Windows is sending out strings for your specific modem. This has the potential for a big difference in what you get from your modem. In addition to that, compare your specific dialup protocol settings. Linux PPP might be escaping a lot of characters, whereas Windows might not be ..

What you're looking for is anything that can cause 1) A different form of handshake in terms of the modems operating, and in terms of how the modem handles line rates after the hand shake (all set by init strings, usually) and 2) Anything that will cause protocol overhead, such as escaped character sequences, lack of compression when compression is supported, etc.
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slyzer · Tux's lil' helper Joined: 12 Oct 2002 Posts: 96

zhenlin · Veteran Joined: 09 Nov 2002 Posts: 1361

I think this is a mozilla 'feature'. If he is using mozilla. Mozilla has a rendering delay, which I still have no idea what for.

474 · l33t Joined: 19 Apr 2002 Posts: 714