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Re: Does DNSMasq (or other DNS/DHCP Servers) Cache Old Addresses?

On Tue, Mar 03, 2009 at 03:56:04AM -0500, Hal Vaughan wrote:
> I'm adding a new system to my LAN.  The DNS is running DNSMasq and is on 
> Etch.  The new system is running Lenny.  I edited the /etc/network/ 
> interfaces file to include the following (other than loopback, the only 
> interface in the file):
> auto eth0
> iface eth0 inet static
> address
> netmask
> gateway
> Originally, when Debian set up the system, it used DHCP instead of a  
> static IP.  This IP address ( is defined on the DNS server 
> in /etc/hosts (which DNSMasq uses for config).  When Debian-Lenny set 
> this up under DHCP, it was assigned the address  I edited 
> the interfaces file to include the above.  If I did 
> "/etc/init.d/networking restart," then it would again get the ...131 
> address.  If I did "ifup eth0" (after doing ifdown first), then it'd get 
> the 111 address it should have, but in at least one case, a few minutes 
> later I checked and it was back to 131.
> I finally shut down the new system and rebooted the DNS server -- after 
> having shut off networking on the new system and restarting DNSMasq on 
> the DNS.  Then I brought up the DNS server, and after that, brought up 
> the new system.  Now it's working and it finally let me define eth0:0 as 
> well (which it kept choking on before).
> So why did it keep getting forced to use the address  
> instead of the one ending in 111?  Did DNSMasq cache the MAC address or 
> did the new workstation cache the info and reuse it automatically?  What 
> was it that the reboot would have restarted that would allow this system 
> to finally get the specified address after the reboot?

The log of dnsmasq is at /var/log/daemon.log .

When your computer asks for an address, does it:

* Uses DHCPDISCOVER but with a preferred IP address?
* Uses DHCPREQUEST directly?

Tzafrir Cohen         | tzafrir@jabber.org | VIM is
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