On a small LAN (< 20 networked devices) with a cento6 5.9 server/dhcp-3.0.5-33.el5_9). I am configuring permanent leases thusly (dhcpd.conf, partial):

  host vega.nouvelle.it      {hardware ethernet 00:1e:c9:47:f1:2d; fixed-address;    }
  host aldebaran.nouvelle.it {hardware ethernet 00:07:84:FB:55:40; fixed-address;   } 

Which works pretty much OK most of the time. Occasionally, however, a lab machine (transient) will get a nailed IP. and, when the owner asks for it, it is then offered a second time leading to conflicts, etc.

I thought that fixing an address would reserve it and protect it from being allocatedo to othe MACs, but, regardless, I surely don't expect the server to offer the same IP twice.

Wrong configuration? Dhcpd bug?


I have always made it a practice to keep fixed addresses outside the DHCP range. That should eliminate this issue. DCHP will offer fixed addresses outside its dynamic range. For fixed addresses, it is common to use infinite or at least very long leases.

Check the DHCP leases file to see if the server has an active lease. They are normally configured not to use DHCP, and therefore would not have a lease.

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