DDNS updates of host entries

[Cyber Dog]

I've configured a fairly standard DDNS setup with ISC bind and dhcpd.
Something I've noticed is that hosts allocated dynamically from the
subnet are updated in bind, but if a machine has a host entry, it is
not updated.  I'm wondering if this is by design, and if it can be
circumvented.  I realize it may not seem logical to use dynamic dns
with static hosts, however I wished to employ it this way just to ease
administration overhead.