Well, this is embarrassing. It turns out RedHat has this documented in their RHEL series, but not in Fedora. It's also not in the man-pages project. The attached patch has a better explanation of the option than the one I submitted earlier today. This text comes from RedHat. On 09/11/2012 02:35 PM, Todd Lewis sent: > The attached "diff -u" formatted patch applies to > http://git.kernel.org/?p=docs/man-pages/man-pages.git;a=blob_plain;f=man5/resolv.conf.5;hb=HEAD > as it existed on 2012-09-11--14:31. > > It adds documentation for the "single-request-reopen" option. This > information was found in the changelog notes > (http://sourceware.org/ml/libc-alpha/2009-10/msg00063.html) from Ulrich > Drepper. The issue and solution were both brought to my attention by a > discussion on our internal mailing list which mentioned this undocumented > feature. Several users indicated they have been suffering from slow DNS > resolutions on machines behind certain firewalls and that this solved > their problems. Seems like others would like to know about it. -- +--------------------------------------------------------------+ / Todd_Lewis@xxxxxxx 919-445-0091 http://www.unc.edu/~utoddl / / How many of you believe in telekinesis? Raise my hand... / +--------------------------------------------------------------+
--- /tmp/man5_resolv.conf.5-orig 2012-09-11 14:25:26.406461617 -0400 +++ /tmp/man5_resolv.conf.5 2012-09-11 16:21:48.264137192 -0400 @@ -168,6 +168,13 @@ (currently 2, see \fI<resolv.h>\fP). The value for this option is silently capped to 5. .TP +.BR single-request-reopen " (since glibc 2.9)" +The resolver uses the same socket for the A and AAAA requests. Some hardware +mistakenly only sends back one reply. When that happens the client sytem will +sit and wait for the second reply. Turning this option on changes this behavior +so that if two requests from the same port are not handled correctly it will +close the socket and open a new one before sending the second request. +.TP .B rotate .\" Since glibc 2.2 sets
