How to configure bootpd on Mac OS X El Capitan (10.11.x)

Okay, solution found.

I googled 'PLCache_read' (the last function listed in /Library/Logs/DiagnosticReports/bootpd_2010-08-12-165459_localhost.crash as having been run by bootpd before the buffer overflow) and the second hit was in Apple's source for bootpd (bsdpd.c, specificall). BSDP_CLIENTS_FILE() is passed the BSDP_CLIENTS_FILE constant, which, looking at the top of the file, is hardcoded as /var/db/bsdpd_clients.

Checking, /var/db/bsdpd_clients, I found a pseudo-plist containing all the NetBoot clients (remember, NetBoot is built upon bootp) and—sure enough!—the last entry was cut off as follows, leaving the file incomplete:

{
        name=NetBoot060
        identifier=

Stopped bootpd (sudo serveradmin stop dhcp), backed up /var/db/bsdpd_clients & emptied it, then started bootpd (sudo serveradmin start dhcp) and no crashing!

After a reboot, all the other related services (incl. NetBoot) are now back up and Server Admin.app is no longer throwing the 'kNetworkError's.

Did you bind the mac to an OSX Server or to Active Directory? If the latter check if the domain ends in .local. If it does there are some known problems with multicast interference on OSX. The process here may work for you: http://www.macwindows.com/TIP-Lion-dot-local-AD-disable-multicast.html

Some Macs just plain aren't happy on an AD network. I've had several iMacs with essentially identical specs and most were fine but 2 kept losing connectivity with the domain controller and had constant kerberos ticket related issues. In this case breaking the mac from the domain and then reconnecting it using Centrify Express resolved the issue. You can find the agent on their website here: http://www.centrify.com/express/free-active-directory-tools-for-linux-mac.asp#agents