Here are several DHCP best practices as collected from various resources including Comp/TIA and Microsoft:
- Always include the entire subnet in the scope (192.168.1.1 – 192.168.1.254, or 172.29.0.1 – 172.29.255.254)
- Add exclusions for ranges which are using static IP addresses, and for future growth area, such as setting aside 10 addresses for printers so they stay within the same general IP address range
- For networks where DHCP services are critcal or for larger networks, consider two DHCP servers configured in an 80/20 split (however, Microsoft Server 2012 has a new provision for redundant DHCP servers)
- Configure active directory credentials to enable DHCP to update the DNS server with IP address information using secure updates.
- Use “server side conflict detection” only when needed – this is a feature which delays DHCP from handing out an address until it has first issued an ICMP ping message to check if the address might already be in use but not known by DHCP already (ie statically assigned within the lease range without an exclusion or active lease).
- Typical DHCP lease time is 8 days, however if you have a separate scope for guest or wireless clients, consider a shorter lease time such as 8 hours; conversely, leases for fixed devices (printers, etc) consider 16-24 days.