3.9. 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 NetDefendOS 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 NetDefendOS
To accomplish DNS resolution, NetDefendOS 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
NetDefendOS:
•
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 3.28. Configuring DNS Servers
In this example, the DNS client is configured to use one primary and one secondary DNS server, having IP
addresses 10.0.0.1 and 10.0.0.2 respectively.
Command-Line Interface
gw-world:/> set DNS DNSServer1=10.0.0.1 DNSServer2=10.0.0.2
Web Interface
1.
Go to System > DNS
2.
Enter the following:
•
Primary Server: 10.0.0.1
•
Secondary Server: 10.0.0.2
3.
Click OK
3.9. DNS
Chapter 3. Fundamentals
144
Summary of Contents for DFL-1600 - Security Appliance
Page 27: ...1 3 NetDefendOS State Engine Packet Flow Chapter 1 NetDefendOS Overview 27 ...
Page 79: ...2 7 3 Restore to Factory Defaults Chapter 2 Management and Maintenance 79 ...
Page 146: ...3 9 DNS Chapter 3 Fundamentals 146 ...
Page 227: ...4 7 5 Advanced Settings for Transparent Mode Chapter 4 Routing 227 ...
Page 241: ...5 4 IP Pools Chapter 5 DHCP Services 241 ...
Page 339: ...6 7 Blacklisting Hosts and Networks Chapter 6 Security Mechanisms 339 ...
Page 360: ...7 4 7 SAT and FwdFast Rules Chapter 7 Address Translation 360 ...
Page 382: ...8 3 Customizing HTML Pages Chapter 8 User Authentication 382 ...
Page 386: ... The TLS ALG 9 1 5 The TLS Alternative for VPN Chapter 9 VPN 386 ...
Page 439: ...Figure 9 3 PPTP Client Usage 9 5 4 PPTP L2TP Clients Chapter 9 VPN 439 ...
Page 450: ...9 7 6 Specific Symptoms Chapter 9 VPN 450 ...
Page 488: ...10 4 6 Setting Up SLB_SAT Rules Chapter 10 Traffic Management 488 ...
Page 503: ...11 6 HA Advanced Settings Chapter 11 High Availability 503 ...
Page 510: ...12 3 5 Limitations Chapter 12 ZoneDefense 510 ...
Page 533: ...13 9 Miscellaneous Settings Chapter 13 Advanced Settings 533 ...