FQDN option

[ccantu at us.ibm.com]

Theory question:
A DHCP client boots and only knows its machine name "mach1".  The DHCP
server has been configured to dish out domain names, option 6 "warped.com".
If the client sends the FQDN option with only "mach1" in its REQUEST
packet, will the server fill in the rest of the name so the data in the
FQDN option is returned as "mach1.warped.com"?

I ask this because the client could have just asked for the option 6 domain
name data and concatenated his machine name and domain name to then do
dynamic DNS updates.  What's good practice? -- Use both so non-DDNS
compliant servers can still give you good info with option 6?  -- Use only
one or the other, but FQDN preferably since it's exactly designed for this
dynamic update business?