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Services
4. (Optional) Cache negative responses
By default, the device's DNS server caches negative responses. Disabling this option may
improve performance on networks with transient DNS results, when one or more DNS servers
may have positive results. To disable:
(config)> service dns cache_negative_responses false
(config>
5. (Optional) Query all servers
By default, the device's DNS server queries all available DNS servers. Disabling this option may
improve performance on networks with transient DNS results, when one or more DNS servers
may have positive results. To disable:
(config)> service dns query_all_servers false
(config>
6. (Optional) Rebind protection
By default, rebind protection is disabled. If enabled, this prevents upstream DNS servers from
returning private IP addresses. To enable:
(config)> service dns stop_dns_rebind false
(config)>
7. (Optional) Allow localhost rebinding
By default, localhost rebinding is enabled by default if rebind protection is enabled. This is
useful for Real-time Black List (RBL) servers. To disable:
(config)> service dns rebind_localhost_ok false
(config)>
8. (Optional) Fallback server
Configure the IP address of the DNS server to be used in the absence of any other server. The
default is 8.8.8.8.
(config)> service dns fallback_server value
(config)>
9. (Optional) Add additional DNS servers
a. Add a DNS server:
(config)> add service dns server end
(config service dns server 0)>
b. Set the IP address of the DNS server:
(config service dns server 0)> address ip-addr
(config service dns server 0)>
c. To restrict the device's use of this DNS server based on the domain, use the domain
command. If no domain are listed, then all queries may be sent to this server.
IX20 User Guide
Configure DNS
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