stale: impossible condition

[Jim Reid]

>>>>> "Thomas" == Thomas Duterme <thomas at madeforchina.com> writes:

    Thomas> Hi folks,

    Thomas> I reloaded my BIND server and found the following error
    Thomas> which I had never come across:

    Thomas> Dec 11 20:14:38 grendel named[10062]: reloading nameserver
    Thomas> Dec 11 20:14:38 grendel named[10062]: /etc/named.conf:18: syntax error near '/' 
    Thomas> Dec 11 20:14:38 grendel named[10062]: pri/51go.com: WARNING SOA refresh value is less than 2 * retry (3600 < 86400 * 2) 
    Thomas> Dec 11 20:14:38 grendel named[10062]: hint zone "" (IN) removed

I would worry about this log message. It means that your server
deleted details about hints for the root zone. It's probably caused by
removing the corresponding zone{} statement from named.conf. And with
the root zone zapped like that, all sorts of bad things can happen.

    Thomas> Dec 11 20:14:38 grendel named[10062]: Ready to answer queries.
    Thomas> Dec 11 20:15:17 grendel named[10062]: stale: impossible condition
    Thomas> Dec 11 20:15:17 grendel named[10062]: stale: impossible condition

    Thomas> Now I know the problem in the config was that I wrote one
    Thomas> instead of two /'s, but those stale errors look
    Thomas> strange....any ideas what they mean?

If you read the code, you'd see that this error message gets printed
whenever the name server finds it has an internal zoneinfo structure
which is not of type master, slave, stub or hint. This inconsistency
is obviously impossible, hence the error message. The error is so
severe that the name server has to shut down because its internal data
structures are corrupted. [By that point it's better to stop than try
to carry on and encounter yet more weird errors or hand out probably
incorrect data.] The reason for that panic is probably because the
zoneinfo struct for the root zone got nuked when you (inadvertedly?)
told the name server to remove it.