The Lazyadmin.com

Regular TLA reader Dan Dill has contributed a great article on DHCP user classes. With ever expanding networks, these little used advanced features in Windows will become more critical to all Admins. Thanks Dan for the great arcticle!

DHCP User Classes allow you to apply additional DHCP options, or a modified set of options, to certain clients on your network as identified by a user class id. For example, you may want to define a different gateway, DNS servers, or lease time for a subset of the computers on your network. This can be accomplished by setting a user class id on those clients (2000 and above) and then configuring that class id appropriately on the local DHCP server.

Note: DHCP vendor classes are somewhat similar in function however are set by the hardware or software vendors and are generally not-settable on clients. Windows clients all have a non-configurable

Continue reading DHCP User Classes

Most admins I talk to run DNS on their Domain Controllers, and most also run DHCP on one or more of them as well. The benefits of AD-Integrated Zones and the small footprint of DHCP allow you to run these services on your DC’s with minimal impact on performance. The risk lies in the way DNS registrations are handled.

If the DC’s computer account is not included in the DNSUpdateProxy group, all registrations in DNS are “owned” by the DC If the DC computer accounts are included, no ownership is assigned. This stands for DNS registrations performed by the DHCP and Netlogon services. It is possible to assign a user account to register all DHCP related DNS registrations. From a command prompt type:

netsh dhcp server set dnscredentials {username} {domainname} {password} n

et stop DHCPServer

net start DHCPServer

Now all DNS registrations triggered by the DHCP service

Continue reading Secure DHCP and DNS Services on Your DC

WINS (Windows Internet Naming Service) is an old outdated IP to NetBIOS translation service that has been supersceeded by DNS (Domain Naming Service) but WINS is still necessary in some enviroments. I found out the hardway recently that not maintaing your WINS database can cause a whole host of weird problems from slow logons, to Exchange not allowing users to logon.

I recently had a corrupt record (or records) in my networks WINS database. This caused login scripts to not run, mapped drives were inaccessible, terminal server users (logging on to the TS with corrupt WINS record) could not access Exchange, and some other minor problems. After removing the terminal server from the domain and removing the server from Active Directory I proceded to re-add it to the domain. It failed when using the NetBIOS name of the domain, however it re-joined without issue when I used the DNS name

Continue reading Maintain Your WINS and DHCP Databases