MFC r318578:
Fix non-recoverable name resolution failures due to negative cache
entries never expiring. This patch honours the negative cache timeout.
To test/experience the failure do the following:
1. Edit /etc/ncd.conf to adjust the cache timeouts as follows:
positive-time-to-live hosts 30
negative-time-to-live hosts 1
2. Ensure that nsswitch.conf hosts line contains something like:
hosts: files cache dns
Note that cache must be specified before dns.
3. Start nscd.
4. Run the following command:
while true; do nc -z -w 3 www.google.com 80; sleep 5; done
5. While running the command, remove or comment out all nameserver
statements in /etc/resolv.conf. After a short while you will notice
non-recoverable name rsolution failures.
6. Uncomment or replace all nameserver statements back into
/etc/resolv.conf. Take note that name resolution never recovers.
To recover nscd must be restarted. This patch fixes this.
PR: 207804
Submitted by: Jov <amutu@amutu.com>
git-svn-id: svn://svn.freebsd.org/base/stable/10@319177
ccf9f872-aa2e-dd11-9fc8-
001c23d0bc1f