Amer Networks E5Web GUI - Manual (Page 236)

3.10. DNS
Overview
A DNS server can resolve a Fully Qualified Domain Name (FQDN) into the corresponding numeric
IP address. FQDNs are unambiguous textual domain names which specify a node's unique
position in the Internet's DNS tree hierarchy. FQDN resolution allows the actual physical IP
address to change while the FQDN can stay the same.
A Uniform Resource Locator (URL) differs from an FQDN in that the URL includes the access
protocol along with the FQDN. For example the protocol might be specified http//: for world
wide web pages.
FQDNs are used in many aspects of a cOS Core configuration where IP addresses are unknown or
where it makes more sense to make use of DNS resolution instead of using static IP addresses.
DNS with cOS Core
To accomplish DNS resolution, cOS Core has a built-in DNS client that can be configured to make
use of up to three DNS servers. The are called the Primary Server, the Secondary Server and the
Tertiary Server. For DNS to function, at least the primary server must be configured. It is
recommended to have both a primary and secondary defined so that there is a backup should
the primary be unavailable.
Features Requiring DNS Resolution
Having at least one DNS server defined is vital for functioning of the following modules in cOS
Core:
• Automatic time synchronization.
• Access to an external certificate authority server for CA signed certificates.
• UTM features that require access to external servers such as anti-virus and IDP.
Example 3.41. Configuring DNS Servers
In this example, the DNS client is configured to use one primary and one secondary DNS server,
having IPv4 addresses 10.0.0.1 and 10.0.0.2 respectively.
Command-Line Interface
Device:/> set DNS DNSServer1=10.0.0.1 DNSServer2=10.0.0.2
InControl
Follow the same steps used for the Web Interface below.
Web Interface
1. Go to: System > Device > DNS
Chapter 3: Fundamentals
236