When I look at the list of domain names in the Windows Server DNS manager, I see a long list of A records associated with clients. Why is it that each client gets an A record - and is it really necessary?
The clients get their DNS records as there is a checkmark on the NIC properties (Right click the NIC, click Properties, highligt "Internet Protocol Version 4 (TCP/IPv4)" and click "Properties". In the properties window, click "Advanced..." and go to the DNS tab. In the bottom there is a checkbox that says "Register this connection's addresses in DNS" which is checked by default. To prevent the clients from auto-create A-records, uncheck this box on each client (or push a script with GPO that disables it for all NICs). As to whether the record is needed or not, well, that depends. I would say that it's good to have, since you then can ping your clients using hostnames, which in many cases can be a helpfull feature both in scripting but also in standard troubleshooting.
Hope it helps
Unchecking the DNS registration option in TCP/IP will prevent that client from registering A record.
Let us assume for a while one of the clients is hosting website www.contoso.com on the client, host name is system-6, with IP address 10.0.0.8 in that scenario the webpage needs one zone in DNS Server with host name system-7, with IP 10.0.0.9 so that rest of the clients will be able to access the webpage. After creating a zone, an A record is created in the same zone which maps to contoso.com, therefore it is mandatory for A record to be in DNS Server.