---
title: "\"No source of entropy\" errors in BIND 9"
slug: "aa-00309"
description: "BIND servers require a source of entropy to perform certain DNSSEC operations."
updated: 2018-10-10T14:43:15Z
published: 2018-10-10T14:43:15Z
canonical: "kb.isc.org/aa-00309"
---

> ## Documentation Index
> Fetch the complete documentation index at: https://kb.isc.org/llms.txt
> Use this file to discover all available pages before exploring further.

# What does "no source of entropy found" or "could not open entropy source foo" mean?

The server requires a source of entropy -- i.e., random numbers -- to perform certain cryptographic operations for DNSSEC or to generate keys for TSIG. These messages indicate that you have no 
source of entropy. On systems that use `/dev/random` or an equivalent device to provide access to the kernel's random number generator, that will be used by default. A source of entropy can also be defined using the `random-device` option in **named.conf**, or specified at compile time using `configure --with-randomdev`.