DHCP Lease & DNS Scavenaging Times - Advice required.
Posted on 2005-03-07
We recently migrated to a new network a few months ago.
80 Windows 2003 servers (Static IP)
250+ Printers / Managed Switches / Routers etc. (Static IP)
1950 XP Desktops (DHCP)
30 XP Laptops (DHCP)
There are two servers acting as both DNS and DHCP servers.
DHCP servers have enough IP's available in their scopes to service many times this number of PC's.
Statistics show that there are only 10% of IP's in use overall and even the heaviest loaded scope is only using 25% of the available IP's (500 in each scope).
Unfortunatley the consultant who designed / configured the system is gone and no longer available.
A few issues have arrisen recently and I discovered that DHCP leases have been set to only 8 hours and scavenging in DNS has not been enabled.
Can someone advise the best practice for DHCP leases and DNS Scavenging periods on a network of this size.
8 hours lease seems very short when there are very few mobile users.
DNS is filling up with duplicate IP addresses for different hosts as the records are never scavenged!
HostA gets assigned IP 10.244.1.50 and registers in DNS.
HostA is switched off for a day.
HostB gets assigned IP 10.244.1.50 and registers in DNS.
(There are now two hosts in DNS with the same IP address)
Ping HostA replies with IP 10.244.1.50 even though it's powered off.
Additional points given for explanation why you would use the lease period / scavenging period you suggest!!