Hello,
When updating the host record, DHCP server searches for a DNS server which is authoritative for the zone matching the domain name of DHCP client.
So if DHCP client is a member of abc.subhro.com domain, DHCP server will look for a DNS server which is authoritative for the zone abc.subhro.com.
If DHCP client is a member of subhro.com domain, DHCP server will look for a DNS server which is authoritative for the zone subhro.com.
Even if we specify a different domain name in DHCP scope option 15 (DNS Domain Name), this behavior would not change. We have tested this point.
Check The Link Bellow:
https://social.technet.microsoft.com/wiki/contents/articles/51810.windows-server-integration-between-dns-and-dhcp.aspx
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