Kerio Tech Firewall6 User Manual
Page 104
Chapter 8
Configuration of network services
104
1.
Time period for keeping DNS logs in the cache is specified individually in each log
(usually 24 hours).
2.
Use of DNS also speeds up activity of the built-in proxy server (see chapter
Clear cache
Click this button to remove all records in the DNS Forwarder’s cache (regardless of their
lifetime). This feature can be helpful e.g. for configuration changes, dial-up testing, error
detection, etc.
Use custom forwarding
Use this option to enable settings for forwarding certain DNS queries to other DNS
servers.
Enable DNS forwarding
DNS forwarder allows forwarding of certain DNS requests to specific DNS servers. This feature
can be helpful for example when we intend to use a local DNS server for the local domain
(the other DNS queries will be forwarded to the Internet directly — this will speed up the
response). DNS forwarder’s settings also play role in configuration of private networks where
it is necessary to provide correct forwarding of requests for names in domains of remote
subnets (for details, check chapter
).
Request forwarding is defined by rules for DNS names or subnets. Rules are ordered in a list
which is processed from the top. If a DNS name or a subnet in a request matches a rule, the
request is forwarded to the corresponding DNS server. Queries which do not match any rule
are forwarded to the “default” DNS servers (see above).
Note: If the Simple DNS resolution is enabled (see below), the forwarding rules are applied only
if the DNS Forwarder is not able to respond by using the information in the hosts system file
and/or by the DHCP lease table.
Clicking on the Define button in the DNS Forwarder configuration (see figure
) opens a dia-
log for setting of rules concerning forwarding of DNS queries.
Figure 8.2
Specific settings of DNS forwarding