Explaining Network Services

Section focuses on Application Service Data

Objectives

You should be able to explain the uses and purposes of the network services protocols DHCP and DNS.

Follow these guidelines to make effective use of network addressing services:

Configure secure DHCP and DNS servers and ensure that all network hosts can contact them, using DHCP relay where appropriate.
Ensure DHCP servers are configured with accurate IP, default gateway, and DNS server parameters for the scopes/subnets that they serve.
Configure reservations or static assignments for hosts that need to be allocated a consistent IP address.
If the address pool is limited, use short lease times to prevent address exhaustion.
Set up primary and secondary name servers to host records for your LAN. These name services should be accessible only by authorized clients.
Configure the appropriate host, MX, and service records for the forward lookup zone on the primary server.
Optionally, configure a reverse lookup zone to allow clients to resolve IP addresses to host names.
Configure the secondary server to obtain up-to-date records periodically through a zone transfer with the primary server.
To resolve client Internet queries, set up a forwarder to pass queries to trusted resolvers on the Internet, such as your ISP’s DNS server or trusted public services such as those from Google or Quad9.
For external DNS, consider using a third-party provider, ideally with a cloud service, to ensure high availability. Without public DNS, your customers will not be able to browse your websites or send you email.
Set up a process for checking that your external DNS records are accurate and working correctly.