Kerio Tech KERIO WINROUTE FIREWALL 6 User Manual download pdf (Page 106)

Chapter 8 Conﬁguration of network services

106

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.

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Kerio Tech KERIO WINROUTE FIREWALL 6 User Manual Page 106