---
title: "When does rndc reconfig flush the cache?"
slug: "aa-00836"
description: "Why does rndc reconfig flush the cache sometimes but not on other occasions?"
tags: ["cache", "resolver", "rndc"]
updated: 2018-10-12T20:32:48Z
published: 2018-10-12T20:32:48Z
canonical: "kb.isc.org/aa-00836"
---

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# 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 that you can make to the configuration that might be incompatible with what has already been cached - and in those circumstances, **named** will also start with a new and empty cache following the reconfig. Here are the settings that, if changed, will result in **rndc reconfig** clearing cache:

- check-names
- zero-no-soa-ttl
- max-cache-size
- max-cache-ttl
- max-ncache-ttl
- dnssec-validation
- dnssec-accept-expired

See also the limitations on views that share cacheThe criteria for whether or not two (or more) views configured in a BIND nameserver may share cache are that the policy settings listed above are consistent between views. [The **attach-cache** option is used to configure cache-sharing](https://kb.isc.org/docs/aa-00835).