iMac 6,1 cannot see netboot images at boot time

[dlrh]

Very odd issue.

I have a mixed bunch of machines. I'm using netboot more often, and have made netboot files for most.

 

I cannot see any netboot image when I try to netboot an older 24" iMac (Mac 6,1). But I *can* see ALL the netboot images when I log in as admin and go to System Preferences, Startup Disk, on these iMacs. In addition, if I do select one as the startup disk, they boot perfectly. What's more, when I then reboot that one, and hold down the option key, I then see the IP address of the server that hosts the netboot images but still no enumeration of the 3 netboot images proper! Never seen that on any other model, so I am a bit baffled by this.

 

I can see all netboot images when I try a netboot from the NEWEST machines, 27" iMacs (and they boot and image just fine).

 

I can see all netboot images when I try a netboot from - gasp - the really old G5 machines (and they also boot and image just fine).

 

And yes, all one subnet. And yes, I take care to make the nbi on the matching hardware.

 

What am I missing here? Seems like I should be able to see the same array of netboot images form these "middle" machines. Firmware? Some obscure setting?

[HodgeHi]

Could there be any filtering configured for the clients?

 

I'm not sure if this would be the case as I've never used the filtering options.

[dlrh]

Could there be any filtering configured for the clients?

 

I'm not sure if this would be the case as I've never used the filtering options.

 

I've never set up anything like filtering. I try to minimize my tinkering with the clients.