Connection Refused to Dynamic DNS Update ?

I'm developing a network tool to configure a group of computers into a
specified network topology / configuration. It works by running a number of
bash subshells in parallel. Without going into gory detail,
the part that occasionally doesn't work is the part that runs 10 subshells
in parallel. Each subshell ssh's to a target host, makes any necessary
changes to the configuration, and then reinitializes the network stuff
(its running on a Linux box, and so executes
/etc/init.d/network stop, followed by /etc/init.d/network start. This
causes each host to request an IP address from its attached DHCP server,
which then dynamically updates the authoritative DNS server with the IP
address information.
Often this works fine, but more often than
I'd like, one or more of the update requests fails, and returns a
"connection refused" error. It appears that the authoritative DNS server
sometimes seems to lose a socket connection or run low or resources or
something. I'm hoping someone reading this may have had this problem and
has come up with a
possible solution. Details are:

Linux: Redhat Linux, release 9; Linux kernel 2.4.20-6
DHCPD Server: dhcpd: V3.0pl1, from the ISC
authoritative DNS server: bind, 9.2.1, from the ISC
relevant excerpt from /var/log/messages on DHCP server system:
Oct 1 14:27:22 rOtto dhcpd: dhcpd startup succeeded

Oct 1 14:28:16 rOtto dhcpd: if IN A Kay.twins.jtrs domain doesn't exist add
10800 IN A Kay.twins.jtrs 135.10.15.250 add 10800 IN TXT Kay.twins.jtrs
"0057dd57f723360485e8d507844aa8f087": connection refused.

Oct 1 14:28:16 rOtto dhcpd: DHCPREQUEST for 135.10.15.250 from
00:0e:0c:07:aa:b9 via eth1

Oct 1 14:28:16 rOtto dhcpd: DHCPACK on 135.10.15.250 to 00:0e:0c:07:aa:b9
(Kay) via eth1

Relevant excerpt from /var/log/messages on DNS server system:

Oct 1 14:26:25 r84 named[4931]: zone twins.jtrs/IN: loaded serial 1

Oct 1 14:26:25 r84 named[4931]: zone localhost/IN: loaded serial 1

Oct 1 14:26:25 r84 named[4931]: running

Oct 1 14:26:25 r84 named[4931]: zone ./IN: sending notifies (serial 37)

Oct 1 14:27:18 r84 named[4931]: client 135.10.13.2#32851: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:27:18 r84 named[4931]: client 135.10.13.2#32851: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:27:18 r84 named[4931]: journal file twins.jtrs.zone.jnl does not
exist, creating it

Oct 1 14:27:29 r84 named[4931]: client 135.10.19.1#32805: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:27:29 r84 named[4931]: client 135.10.19.1#32805: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:27:29 r84 named[4931]: client 135.10.12.1#32803: updating zone
'twins.jtrs/IN': update failed: 'name not in use' prerequisite not satisfied
(YXDOMAIN)

Oct 1 14:27:29 r84 named[4931]: client 135.10.12.1#32803: updating zone
'twins.jtrs/IN': deleting an rrset

Oct 1 14:27:29 r84 named[4931]: client 135.10.12.1#32803: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:27:30 r84 named[4931]: client 135.10.16.1#32854: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:27:47 r84 named[4931]: client 135.10.14.1#32838: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:27:47 r84 named[4931]: client 135.10.14.1#32838: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:27:47 r84 named[4931]: client 135.10.14.2#32824: updating zone
'twins.jtrs/IN': update failed: 'name not in use' prerequisite not satisfied
(YXDOMAIN)

Oct 1 14:27:47 r84 named[4931]: client 135.10.14.2#32824: updating zone
'twins.jtrs/IN': deleting an rrset

Oct 1 14:27:47 r84 named[4931]: client 135.10.14.2#32824: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:28:05 r84 named[4931]: client 135.10.24.1#32838: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:28:05 r84 named[4931]: client 135.10.24.1#32838: updating zone
'twins.jtrs/IN': adding an RR

Oct 1 14:28:05 r84 named[4931]: client 135.10.14.2#32824: updating zone
'twins.jtrs/IN': update failed: 'name not in use' prerequisite not satisfied
(YXDOMAIN)

Oct 1 14:28:05 r84 named[4931]: client 135.10.14.2#32824: updating zone
'twins.jtrs/IN': deleting an rrset

Note that in the above output, there are no messages relatiing to client
135.10.15.1, which is the DHCP server.
I can provide copies of relevant named.conf, dhcpd.conf files, etc. if
needed.

This is not a consistently repeatable problem, and sometimes its one system
that gets a "connection refused" error, and sometimes its a different one.
This, to me, suggests that it may be related to some type of race or timing
condition on the DNS server, but I am not familiar with the BIND code,
and its big enough that trying to learn it or study it seems a doable but
definitely non-trivial task.

Any help or suggestions would be much appreciated.
Dennis Newbold
dennisn@pe.net

Any help or suggestions would be appreciated.