5.3 DNS Forwarder

Figure 5.10 Specific settings of DNS forwarding

DNS server can be specified for:

DNS name — queries requiring names of computers will be forwarded to this DNS server (so called A queries)

a subnet — queries requiring IP addresses of the particular domain will be forwarded to the DNS server (reverse domain — PTR queries)

Click on the Add or the Edit button to open a dialog where custom DNS forwarding rules can be defined.

The Name DNS query option allows specification of a rule for name queries. Use the If the queried name matches entry to specify a corresponding DNS name (name of a host in the domain).

It is usually desirable to forward queries to entire domains rather than to specific names. Specification of a domain name may therefore contain * wildcard symbol (asterisk — substitutes any number of characters) and/or ? (question mark — sub- stitutes a single character). The rule will be applied to all names matching with the string (hosts, domains, etc.).

Example: DNS name will be represented by the string ?erio.c*. The rule will be applied to all names in domains kerio.cz, cerio.com, aerio.c etc., such as on www.kerio.cz, secure.kerio.com, www.aerio.c, etc.

Warning: It is necessary that the expression specified in the If the query contains domain entry is an entire DNS name! If, for example, the kerio.c* expression is introduced, only names kerio.cz, kerio.com etc. would match the rule and host names included in these domains (such as www.kerio.cz and secure.kerio.com) would not!

63

Page 63
Image 63
Kerio Tech Firewall6 manual Specific settings of DNS forwarding