DHCP / DNS

The normal no-refresh inerval and refresh would both be 7 days if using an 8 day lease.

you should really leave them as defaults - the only time to really drop them is if you drop the lease time too - they go hand in hand in most environments

Guys,

I have two DHCP servers in NY office. The scopes are divided 50-50 on both servers. By default dhcp leases expires in 8 days. I read the following instructions below and then I made the  

DNS
server aging/scavenging

no-refresh interval is 4 days
refresh interval is 4 days

http://technet2.microsoft.com/windowsserver/en/library/528aa0a4-e5b4-45da-9769-1d00ef636bb31033.mspx?mfr=true

DHCP server
 4 days (half of the lease interval, which is 8 days by default)

Note

" Refresh attempts are only made by the DHCP servers configured to perform DNS dynamic updates on behalf of their clients (for example Windows 2000 Server DHCP server and Windows Server 2003 DHCP server). The period is based on the frequency in which DHCP clients renew their IP address leases with the server. Typically, this occurs when 50% of the scope lease time has elapsed. If the DNS default scope lease duration of 8 days is used, then the maximum refresh period for records updated by DHCP servers on behalf of clients is 4 days.