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Windows Lesson 05 - DHCP/DNS

Summary

We're going to learn how to use and configure two network services on our network.  DHCP is used to configure our clients IP information automatically, and DNS is used to help those clients find network services and devices.

DHCP

Dynamic Host Configuration Protocol (DHCP) is used to automatically assign IP information to network devices.  You can install the DHCP role on any server on your domain.  Once installed you can create a scope.  A Scope is the list of IP addresses and setting you're handing out to your clients.  Below we see a clean install on DHCP without any scopes configured.

Once you use the new scope wizard you'll have a range of address ready to be handed out to your clients.

With DHCP we can hand out more then IP addresses, we can hand out other IP settings, like the gateway address, or DNS settings.

You can make sure a device receives the same IP address each time be creating a reservation.  You use the devices MAC address to assign it the same IP.  You can use the new reservation wizard to create your reservation.

One of the settings you can tweak is the lease duration.  By default the scope wizard will use 8 days for the lease duration.  You can change the value of this depending on your environment.  If you have an environment where there's a high turnover of people and devices then you may want to set the lease duration to a shorter time.  For example if you have a coffee shop and you offer free wifi you wouldn't want to tie up an address for 8 days for each customer.  Alternatively, if you have a network that doesn't change often you may want to increase the duration to reduce renewal traffic.  


DNS

DNS is used to help your clients find computers and services.  DNS is made up of two sections, there are Forward Lookup Zones, and Reverse Lookup Zones.  
  • Forward Lookup Zone - Hostname to IP
  • Reverse Lookup Zone - IP to Hostname
When we installed DNS during the installation of Active Directory a forward lookup zone was created, but not a reverse lookup zone.  You can use the new zone wizard to add a reverse lookup zone.  When adding a reverse lookup zone you have to provide a class C network ID for the range it will store.

Once you have a reverse lookup zone you can add pointer (PTR) records that point the IP addresses to your hostnames.


In the forward lookup zone we have many typs of records, like host (A) records, or services (SRV) records.  Host records resolve hostnames to IP addresses.


Service records tell the client where to find networks services.


DHCP and DNS Working Together

DHCP and DNS work well together.  We can have DHCP let DNS know when a new client has joined the network and it will add that information to the forward and reverse lookup tables.  

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