summaryrefslogtreecommitdiff
path: root/FAQ
diff options
context:
space:
mode:
Diffstat (limited to 'FAQ')
-rw-r--r--FAQ21
1 files changed, 21 insertions, 0 deletions
diff --git a/FAQ b/FAQ
index 279b6e8..cb74994 100644
--- a/FAQ
+++ b/FAQ
@@ -409,6 +409,27 @@ A: Yes, as a DNS server, dnsmasq will just work in a vserver.
refer to the vserver documentation for more information).
+Q: What's the problem with syslog and dnsmasq?
+
+A: In almost all cases: none. If you have the normal arrangement with
+ local daemons logging to a local syslog, which then writes to disk,
+ then there's never a problem. If you use network logging, then
+ there's a potential problem with deadlock: the syslog daemon will
+ do DNS lookups so that it can log the source of log messages,
+ these lookups will (depending on exact configuration) go through
+ dnsmasq, which also sends log messages. With bad timing, you can
+ arrive at a situation where syslog is waiting for dnsmasq, and
+ dnsmasq is waiting for syslog; they will both wait forever. This
+ problem is fixed from dnsmasq-2.39, which introduces asynchronous
+ logging: dnsmasq no longer waits for syslog and the deadlock is
+ broken. There is a remaining problem in 2.39, where "log-queries"
+ is in use. In this case most DNS queries generate two log lines, if
+ these go to a syslog which is doing a DNS lookup for each log line,
+ then those queries will in turn generate two more log lines, and a
+ chain reaction runaway will occur. To avoid this, use syslog-ng
+ and turn on syslog-ng's dns-cache function.
+
+