On Wed, May 28, 2014 at 04:34:23PM +0200, Denys Vlasenko wrote: > On Tue, May 27, 2014 at 9:34 AM, muddyboot <emu...@gmail.com> wrote: > > Hi, I found nslookup resolve very slow on x86_64 system , it cost 5 seconds > > or longer almost everytime. > > > > Tested OS: Debian 7 x86_64 with kernel 3.2.5 & LFS x86_64 with kernel 3.12 > > > > No IPv6 enabled in kernel config. > > DNS server works fine > > nslookup program from bind-9.7 works fine > > nslookup from busybox test on i686 system OK > > > > target busybox version: 1.17.4、1.20.2、1.21.1、1.22.1 > > > > Any response for this problem is great appreciated. > > bbox nslookup uses libc to perform the lookup. > > glibc maintainers known to be quite.. er.. stubborn > about how DNS should work. > > For example, they insist that IPv6 DNS requests must be sent > even if the machine has no IPv6 support in kernel > (let alone a more typical case where machine > has no IPv6 connectivity). > > Your DNS server does not respond to IPv6 requests, > but glibc waits for them.
Unless the caller requested AI_ADDRCONFIG or requested AF_INET explicitly as opposed to AF_INET6, it's required to do this. And I don't think it's a bug. It may be useful to know all DNS results even if some of them (v6) won't be used for your current client setup. The bug is in whatever broken nameserver is ignoring AAAA requests rather than properly looking them up and returning a result. However, it may be nice to have an option for bb nslookup to turn off v6 lookups if such an option doesn't already exist. Rich _______________________________________________ busybox mailing list busybox@busybox.net http://lists.busybox.net/mailman/listinfo/busybox
