Introduction

If you require a Cisco device to act as a DHCP server. Do ensure you either set a database URL or the no ip dhcp conflict logging option otherwise the server can fail leaving your users free to complain that "the internet is broken". I prefer to use a database agent.

Solution

Now you can either use local flash or a tftp/ftp server or of course both. You just need a config line using the following url format:

ip dhcp database tftp://<tftp server address>/DHCP_Binding/dhcp_db

ip dhcp database flash0:/DHCP_Binding/dhcp_db

Of course you need to check which flash you have on your router and make the location first using standard UNIX commands.

mkdir flash0:/DHCP_Binding

You need to do whats required on the TFTP server side also and test if you are using a separate server as a logging destination. Once these are implemented then you can check if the file exists. It is just a plain text file. You can also check the status of the dhcp server using:

sh ip dhcp database

Some other useful docs: http://networkbroadcast.co.uk/2013/03/dhcp-and-conflict-logging/ http://www.cisco.com/c/en/us/td/docs/ios-xml/ios/ipaddr_dhcp/configuration/12-4t/dhcp-12-4t-book/config-dhcp-server.html