Symantec Security 5600 Series, Security 5400 Series,Clientless VPN 4400 Series, Administration Manual

Page: 140 / 861

140 Establishing your network
About the security gateway’s implementation of DNS
Configuring a caching name server with an internal name server
You can also configure a caching name server to work in conjunction with an internal name server, as
shown in
Figure 5-10 . In this case, the client resolvers from the inside network use the internal name
server to answer requests. The internal name server forwards any requests it does not know to the
caching name server on the security gateway. External name server requests that query the caching
name server on the security gateway do not receive a response, as the security gateway is not
authoritative.
Figure 5-10 Example network layout with a caching name server with an internal name server
Table 5-1 shows the records to configure to set up a caching name server with an internal name server.
Configuring an authoritative name server for a domain
An authority record defines the name server that is responsible for a given domain. The DNS proxy is
only authoritative for those domains and networks that are defined through the DNS Record
Properties dialog box. This name server has the physical zone records for the domain, and responds to
all DNS requests for zone information. For any given domain, there is only one name server designated
as the primary DNS server.
One common message that displays on the SGMI when a lookup is performed is that the response is
non-authoritative. This means that the DNS reply did not come directly from the authoritative name
server. Instead, the local or intermediate DNS server was contacted (if applicable) and it returned a
cached version of the record.
Table 5-1 Caching name server configuration options
Where to configure Which resource records to configure
Security gateway There are no resource records to configure.
The loopback address and the inside interface for an internal name server are
configured automatically after you run the System Setup Wizard.
Internal name server Configure a forwarder record.
See “Pointing to an external name server with a DNS forwarder record” on page 146.