DNS Resolver

Configuration Options > Networking > DNS Resolver

DNS Resolver


Option	Description
	Resolver
Local Domain Expansion	Enables or disables local domain expansion so that Content Gateway can attempt to resolve unqualified hostnames by expanding to the local domain. For example, if a client makes a request to an unqualified host named hostx, and if the WCG local domain is y.com, Content Gateway expands the hostname to hostx.y.com.
	Host Database
DNS Lookup Timeout	Specifies the maximum number of seconds the proxy can wait for a lookup response from the Domain Name Server.
Foreground Timeout	Specifies how long DNS entries can remain in the database before they are flagged as stale. For example, if this timeout is 24 hours and a client requests an entry that has been in the database for 24 hours or longer, the proxy refreshes the entry before serving it. Caution: Setting the foreground timeout too low might slow response time. Setting it too high risks accumulation of incorrect information.
Failed DNS Timeout	Specifies how long, in seconds, that a host name is retained in the failed DNS lookup cache. When the timeout expires, the host name is removed from the cache and the next request for that host name is sent to the DNS server.
	Split DNS
Split DNS	Enables or disables the Split DNS option. When enabled, Content Gateway can use multiple DNS servers, depending on your security requirements. For example, you can configure the proxy to look to one set of DNS servers to resolve hostnames on your internal network, while allowing DNS servers outside the firewall to resolve hosts on the Internet. For information about using Split DNS, see Using the Split DNS option.
Default Domain	Specifies the default domain used for split DNS requests. If a hostname does not include a domain, Content Gateway appends the default domain name to the hostname before choosing which DNS server to use.
DNS Servers Specification	Displays a table listing the rules in the splitdns.config file that control which DNS server the proxy uses for resolving hosts under specific conditions.
Refresh	Updates the table to display the most up-to-date rules in the splitdns.config file. Click this button after you have added or modified rules with the configuration file editor.
Edit File	Opens the configuration file editor so that you can edit and add rules to the splitdns.config file. The configuration file editor page is described below.
	splitdns.config Configuration File Editor
rule display box	Lists the splitdns.config file rules. Select a rule to edit it. The buttons on the left of the box allow you to delete or move the selected rule up or down in the list.
Add	Adds a new rule to the rule display box at the top of the configuration file editor page. Enter information in the fields provided before you click this button.
Set	Updates the rule display box at the top of the configuration file editor page. Select a rule and change its properties before you click this button.
Primary Destination Type	Specifies that DNS server selection is based on the destination domain (dest_domain), destination host (dest_host), or on a regular expression (url_regex).
Primary Destination Value	Specifies the value of the primary destination. Place the symbol "!" at the beginning of the value to specify the NOT logical operator.
DNS Server IP	Specifies the DNS server to use with the primary destination specifier. You can specify a port using a colon (:). If you do not specify a port, 53 is used. You can specify multiple DNS servers separated by spaces or by semicolons (;).
Default Domain Name (Optional)	Specifies the default domain name to use for resolving hosts. Only one entry is allowed. If you do not provide the default domain, the system determines its value from /etc/resolv.conf.
Domain Search List (Optional)	Specifies the domain search order. You can specify multiple domains separated by spaces or by semicolons (;). If you do not provide the search list, the system determines the value from /etc/resolv.conf.
Apply	Applies the configuration changes.
Close	Exits the configuration file editor. Click Apply before you click Close; otherwise, all configuration changes are lost.

Configuration Options > Networking > DNS Resolver

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