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1 What to do with a misbehaving BIND server Featured

Sometimes a named process will appear to behave abnormally - for example it uses more CPU or memory than usual (or less), emits unexpected error messages, doesn't respond to queries, or responds negatively or late. It's tempting just to restart named or to…

2 What to do if your BIND or DHCP server has crashed Featured

If your BIND or DHCP server crashes (i.e. the daemon terminates unexpectedly), collecting the evidence available and submitting to us is vital if we are to help diagnose the problem and provide a solution. Below is a list of files/information to collect after…

3 Why does dig report one more record in the additional section of a query response than I am seeing?

This is not a bug, and it is not new behavior, although those newly upgrading to BIND 9.9 from earlier versions may have encountered it for the first time there. From BIND 9.9.0 and newer, dig has changed its defaults: dig now defaults to using options "+adflag"…

4 How do I flush or delete incorrect records from my recursive server cache?

Sometimes a recursive server may have incorrect records in its cache. These may be as a result of an error made by a zone administrator, or as a result of a deliberately engineered cache poisoning attack. For cache problems relating to DNSSEC validation,…

5 Why does my authoritative-only nameserver try to query the root nameservers?

Check first that recursion really is disabled: recursion no; This will prevent your nameserver from performing iterative queries on behalf of any client queries that it receives, but it won't prevent your server from needing to make queries of its own in…

6 When does rndc reconfig flush the cache?

Why does rndc reconfig flush the cache sometimes but not on other occasions? Usually when issuing rndc reconfig to make changes to a running BIND 9 nameserver, you expect it to retain the current working cache of learned RRsets. However, there are a few changes…

7 How do I configure multiple views to share the same recursive cache?

The attach-cache option is used to configure cache-sharing between views. attach-cache cache_name; By default, each view has its own unique cache. When using the attach-cache option, you can specify a name for the cache that named creates for a view. If multiple…

8 Why does named log an error 'disabling RFC 1918 empty zones' when starting up?

In BIND 9.6-ESV-R5, 9.7.4, 9.8.1 (and newer versions of 9.6-ESV, 9.7 and 9.8 that supersede them), the warning message below may be encountered when named is starting: Warning: 'empty-zones-enable/disable-empty-zone' not set: disabling RFC 1918 empty zones…

9 Why are queries for some PTR records no longer forwarded since upgrading to BIND 9.9.0?

This behaviour may be encountered due to the introduction of automatic empty zones for RFC 1918 prefixes if you are using IP addresses within the RFC 1918 private address space. BIND provides a number of empty zones that are automatically configured and loaded…

10 What does named log message "deleted from unreachable cache" mean?

An example of the messages being logged is: 02-Aug-2012 07:58:20.601 general: info: master 192.0.2.4#53 (source 192.0.2.8#0) deleted from unreachable cache BIND maintains a cache of unreachable masters to which it refers when handling a zone refresh. If a…

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