Date: Thu, 31 Jul 2003 17:16:46 +0100 From: Matthew Seaman <m.seaman@infracaninophile.co.uk> To: Aaron Siegel <bulk_mail@siegel-tech.net> Cc: freebsd-questions@freebsd.org Subject: Re: Resolving domain names in KDE apps Message-ID: <20030731161646.GF23108@happy-idiot-talk.infracaninophile.co.uk> In-Reply-To: <200307310910.43035.bulk_mail@siegel-tech.net> References: <200307310941.20889.froese@mtu.edu> <200307310910.43035.bulk_mail@siegel-tech.net>
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--wtjvnLv0o8UUzur2 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Content-Transfer-Encoding: quoted-printable On Thu, Jul 31, 2003 at 09:10:42AM -0600, Aaron Siegel wrote: > Hello Robert >=20 > I have been using FreeBSD 5.1 RELEASE and Konqueror without any noticeab= le=20 > problems with speed or name resolution. The problem I have are related = to=20 > browser issue: not haveing support for shockwave, scripting problems, and= =20 > poorly develop sites that do not work well with the KHTML and Mozilla=20 > engines. The site you referenced does load slowly for me, but I think is = do=20 > to the site and it is defiantly not a result of the operating system or K= DE.=20 > The webpage does load some files form ad.ca.doubleclick.net see code bel= ow. >=20 >=20 > <TD width=3D"468" height=3D"60" valign=3D"middle"> > <SCRIPT language=3D"JavaScript1.1"=20 > SRC=3D"http://ad.ca.doubleclick.net/N3081/adj/ccn.com/van/indexbanner;loc= =3DtheTop;sz=3D468x60;stile=3D1;dcopt=3Dist;kw=3Dvan;ord=3D9?"></SCRIPT><NO= SCRIPT><a=20 > TARGET=3D"_top"=20 > HREF=3D"http://ad.ca.doubleclick.net/N3081/jump/ccn.com/van/indexbanner;l= oc=3DtheTop;sz=3D468x60;stile=3D1;kw=3Dvan;ord=3D9?"><IMG=20 > NAME=3D"i_banner" ALIGN=3D"TOP" BORDER=3D"0" VSPACE=3D"0" HSPACE=3D"0" WI= DTH=3D"468"=20 > HEIGHT=3D"60"=20 > SRC=3D"http://ad.ca.doubleclick.net/N3081/ad/ccn.com/van/indexbanner;loc= =3DtheTop;sz=3D468x60;stile=3D1;kw=3Dvan;ord=3D9?"></a></NOSCRIPT></TD></TR> >=20 > On Thursday 31 July 2003 07:41 am, Robert Froese wrote: > > Hello, > > > > I'm a new FreeBSD user with a performance issue. I've installed 5.1R a= nd > > KDE. I've also installed Phoenix from the ports collection. When I'm us= ing > > Konqueror or Phoenix to browse certain web sites they take forever to l= oad. > > > > It appears the problem is associated with resolving domain names. Whil= e I > > wait (minutes!) for a problematic page to load, Phoenix will report in = the > > notices bar at the bottom "Resolving host ...". There's no CPU or netw= ork > > bottleneck and the problem is reproducable in either browser with the s= ame > > web sites. It seems also to relate to situations where one web page ca= lls > > another for part of the content (e.g., www.vancouversun.com tries to lo= ad > > from ad.ca.doubleclick.net). > > > > If I open up a shell window and ask FreeBSD to resolve the same domain > > names with "host" they resolve instantly. So the problem has something= to > > do with the way the package for KDE talks with BSD. > > > > Any advice would be greatly appreciated! Here's why it's so slow: % dig ad.ca.doubleclick.net IN AAAA =20 ; <<>> DiG 8.3 <<>> ad.ca.doubleclick.net IN AAAA=20 ;; res options: init recurs defnam dnsrch ;; res_nsend to server default -- 127.0.0.1: Operation timed out Here's how it should have responded: % dig www.bbc.com IN AAAA =20 ; <<>> DiG 8.3 <<>> www.bbc.com IN AAAA=20 ;; res options: init recurs defnam dnsrch ;; got answer: ;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 2 ;; flags: qr rd ra; QUERY: 1, ANSWER: 0, AUTHORITY: 0, ADDITIONAL: 0 ;; QUERY SECTION: ;; www.bbc.com, type =3D AAAA, class =3D IN =20 ;; Total query time: 141 msec ;; FROM: happy-idiot-talk.infracaninophile.co.uk to SERVER: default -- = 127.0.0.1 ;; WHEN: Thu Jul 31 16:37:51 2003 ;; MSG SIZE sent: 29 rcvd: 29 There's absolutely nothing wrong with your systems. The problem is with the doubleclick.net DNS servers which incorrectly fail to respond at all to queries for resource record types they don't know about. That means you have to sit and wait until the request times out, which takes something like 30s. The bbc.com web servers do the right thing, which is to send a negative response, and all in under 150 ms as you can see. Now, the RFC defining the AAAA resource record was published nearly 10 years ago, so there is really absolutely no excuse for doubleclick.net to be running anything so broken. However, if you're running a webserver using the Mozilla engine, the simple response is to right-click on the advert and select "block images from this server". Note that there will be no problem resolving those names using host(1) as that does an A lookup (IPv4) by default. Try: % host -t aaaa ad.ca.doubleclick.net At this point you're maybe asking what a AAAA record is and why your web browser should be trying to look one up. The answer is that AAAA is the IPv6 equivalent of an A record: ie. it returns the IPv6 IP number corresponding to the hostname. The reason that Mozilla is doing an IPv6 lookup is that that is what the standards say to do nowadays: see getaddrinfo(3), RFC 2553 and http://www.opengroup.org/onlinepubs/007904975/functions/getaddrinfo.html (You may need to register in order to see that web page). Cheers, Matthew PS. The irony of it all is that AAAA resource records are themselves probably going to be phased out in favour of the A6 resource type in the not to distant future, which does essentially the same job, but has various other advantages beyond the scope of this e-mail to go into. See http://www.faqs.org/rfcs/rfc2874.html if you're interested. --=20 Dr Matthew J Seaman MA, D.Phil. 26 The Paddocks Savill Way PGP: http://www.infracaninophile.co.uk/pgpkey Marlow Tel: +44 1628 476614 Bucks., SL7 1TH UK --wtjvnLv0o8UUzur2 Content-Type: application/pgp-signature Content-Disposition: inline -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.2.2 (FreeBSD) iD8DBQE/KUDtdtESqEQa7a0RAiGbAJ9cMNY7GRGS5c7naI+ZsdLk4TJfcwCggieP 8kHoigjhutevYIXthJ6zMwo= =gzm4 -----END PGP SIGNATURE----- --wtjvnLv0o8UUzur2--
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