DHCP version compatability in failover configuration

[Doug Caviness]

Since members of this list steered me right the last time I posted a
question (thanks to both Glenn Satchell and Simon Hobson) I will ask for
a little more hand-holding. Figuratively, not literally. 
 

I have two Solaris SPARC server running v3.0.1 in a failover
configuration. I want to upgrade them both to v3.0.5. Can I do them one
at a time or should I bring both down, thus bringing all of DHCP down,
and upgrade simultaneously? Are there issues with v3.0.1 and v3.0.5
"talking" to each other to keep the leases synchronized?

 

Thanks.