Why DHCP Ain’t as Good as it Used to Be

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phone-37856_1920Why DHCP ain’t as good as it used to be.

DHCP used to be the go-to protocol when setting up computers and printers.

These days you may want to use static IPs for printers and maybe even computers if you user RDP (Remote Desktop Protocol).

DHCP (Dynamic Host Configuration Protocol) allows a server to hand out IPs and network information to devices joining your network. Often this is handled by a router. The router may be built into your cable modem on a home network.

Every device on your network requires a unique IP so that the requests for network and web resources get routed correctly.

The alternative is to set up static IPs, in which case, you manually enter pertinent information like the gateway (router), DNS servers, and a static IP that is not in the DHCP IP pool or previously assigned.

DHCP is much simpler especially is you have lots of devices coming and going. In fact, it is easier to enter a static IP after first reviewing a CMD prompt of ipconfig for the DHCP assigned values.

On a domain, this is best done by the server.

System

For our discussion, we will assume a small single server (server) but the principles apply to most DHCP servers.

Windows Server 2008 R2 Standard
DC (domain controller) for corp.domain.com
AD (Active Directory)
connected to the Internet via a cable router.

DNS--maskedVital Information

The vital pieces of information that DHCP must supply on a domain are the IP, gateway router, DNS servers, and domain.

DHCP scope options
003 router -192.168.0.1
006 DNS servers – 192.168.0.253 (our DC)
015 domain name – corp.domain.com

address pool : 192.168.0.50 -192.168.0.99

Typically we save a few IPs for static machines like servers, routers, and printers. For our system, we will reserve IPs below 192.168.0.50. For larger networks you may need multiple scopes and/or wider ranges.

The domain name should match the domain name in DNS forward lookup zone. You can find DNS & DHCP sections in Server Manager. Expand sections and right-click to select properties to  find & edit information.

Troubleshooting DHCP

For our demo system, we are assuming that server was in another domain prior (domain.com) to becoming DC (domain controller) for corp.domain.com. Since DNS forwarder shows corp.domain.com as the domain we will edit our DHCP name accordingly.

Our demo system also had a bogus router 0.0.0.0 so we delete the information and add our gateway 192.168.0.1.

These sorts of problems occur when the server goes from member server to domain controller of another domain.

In Conclusion

DHCP is still very useful so you will want to take advantage of it as much as possible.

Tip: Even if you use static IPs you may want to look at something that’s already on your network to see how DHCP set it up.

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