DNS server not responding, lwresd not servicing incoming queries

Kory Keith korykeith.tx at gmail.com
Mon Dec 5 23:06:29 UTC 2016

My symptoms are like this: if I'm sending queries from my application at a
slow, but steady rate, all is well for cached entries and when the server
responds in a timely manner. When the server does not respond or not in a
timely manner, my application receives no responses (even for cached
entries) for sometimes seconds at a time - based on the configured

In lwdclient.c, I am using the default values of 2 tasks (NTASKS) and 2
clients per task (NRECV).

If I run a series of queries that all miss the cached entries and result in
an external query, it appears from studying the code that those clients are
blocked in the running state until a response is received or until the
request times out.

The only time I see the client returning to the IDLE list is after sending
a reply (other than the few error scenarios such as failed socket read,

If this is the intended behavior, am I correct that a network issue where a
DNS server (or servers) are non-responsive or slow to respond could cause
all traffic to back up coming into lwresd, even for the cached entries?

Thank you,

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