DHCP sends update on behalf of client with TTL zero

Hello,

We have a DHCP server configured which sends dynamic updates on behalf of client which are ILO IP's.

I can see that the updates are sent with TTL value of zero in a packet capture but I dont see the record in the DNS server.

The DNS server is configured for secure dynamic updates. DHCP is configured with the "Always dynamically update A and PTR"

DHCP server computer account is added to the DnsProxyUpdate group.

I refered to this document and the settings matched.

http://msmvps.com/blogs/acefekay/archive/2009/08/20/dhcp-dynamic-dns-updates-scavenging-static-entries-amp-timestamps-and-the-dnsproxyupdate-group.aspx

I want to understand TTL zero update is causing the A records to not show up in DNS.