DHCP server answers with delay

[Denis Taranushin]

> If you're not using DDNS, try explicitly setting it to off. The default
> is on, which can sometimes cause the delays described.

# The ddns-updates-style parameter controls whether or not the server will
# attempt to do a DNS update when a lease is confirmed. We default to the
# behavior of the version 2 packages ('none', since DHCP v2 didn't
# have support for DDNS.)
#ddns-update-style none;

It looks like none-supported =)
But thanks, I'll try it uncomment.