Kerio Tech KERIO WINROUTE FIREWALL 6, Administrator'S Manual

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Chapter 8 Configuration of network services
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Note:
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 WinRoute’s non-transparent proxy server
(see chapter 8.4 ).
Clear cache
Clear-out of all records from the DNS 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
(see below).
Simple DNS resolution
The DNS module can answer some DNS requests on its own, typically requests regarding local
host names. In local network, no other DNS server is required, neither it is necessary to save
information about local hosts in the public DNS. For hosts configured automatically by the
DHCP protocol (see chapter 8.2 ), the response will always include the current IP address.
Before forwarding a query...
These options allow setting of where the DNS module would search for the name or IP
address before the query is forwarded to another DNS server.
• ’hosts’ file — this file can be found in any operating system supporting TCP/IP.
Each row of this file includes host IP addresses and a list of appropriate DNS
names. When any DNS query is received, this file will be checked first to find out
whether the desired name or IP address is included. If not, the query is forwarded
to a DNS server.
If this function is on, the DNS module follows the same rule. Use the Edit button
to open a special editor where the
hosts
file can be edited within the Administra-
tion Console even if this console is connected to WinRoute remotely (from another
host).
• DHCP lease table — if the hosts within local network are configured by the DHCP
server in WinRoute (see chapter 8.2 ), the DHCP server knows what IP address was
defined for each host. After starting the system, the host sends a request for IP
address definition including the name of the host.
The DNS module can access DHCP lease tables and find out which IP address has
been assigned to the host name. If asked to inform about the local name of the
host, DNS Forwarder will always respond with the current IP address. Actually,
this is a method of dynamical DNS update.
Note: If both options are disabled, the DNS module forwards all queries to other DNS
servers.