Domain Name System
The Domain Name System (DNS) translates domain names into IP addresses for the purpose of locating and addressing hosts.
As a DNS client, the device resolves domain names to IP addresses through the use of one or more configured DNS servers.
DNS Settings
Use the DNS Settings page to enable the DNS feature, configure the DNS servers and set the default domain used by the device. To configure the DNS Settings, follow these steps;
Procedure
Step 1 |
Click General IP Configuration > DNS > DNS Settings. |
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Step 2 |
In Basic Mode, enter the parameters:
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Step 3 |
In Advanced Mode, enter the parameters.
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Step 4 |
Click Apply. The Running Configuration file is updated. The DNS Server Table displays the following information for each DNS server configured:
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Step 5 |
Up to eight DNS servers can be defined. To add a DNS server, click Add. |
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Step 6 |
Enter the parameters.
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Step 7 |
Click Apply. The DNS server is saved to the Running Configuration file. |
Search List
The search list can contain one static entry defined by the user in the DNS Settings and dynamic entries received from DHCPv4 and DHCPv6 servers.
To view the domain names that have been configured on the device, click General IP Configuration > DNS > Search List.
The following fields are displayed for each DNS server configured on the device.
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Domain Name—Name of domain that can be used on the device.
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Source—Source of the server’s IP address (static or DHCPv4 or DHCPv6) for this domain.
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Interface—Interface of the server’s IP address for this domain.
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Preference—This is the order in which the domains are used (from low to high). This effectively determines the order in which unqualified names are completed during DNS queries.
Host Mapping
Host name/IP address mappings are stored in the Host Mapping Table (DNS cache).
This cache can contain the following type of entries:
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Static Entries—These are mapping pairs that manually added to the cache. There can be up to 64 static entries.
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Dynamic Entries—Are mapping pairs that are either added by the system as a result of being used by the user, or an entry for each IP address configured on the device by DHCP. There can be 256 dynamic entries.
Name resolution always begins by checking static entries, continues by checking the dynamic entries, and ends by sending requests to the external DNS server. Eight IP addresses are supported per DNS server per host name.
To add a host name and its IP address, complete the following:
Procedure
Step 1 |
Click General IP Configuration > DNS > Host Mapping. |
Step 2 |
If required, select one of the following options from Clear Table to clear some or all of the entries in the Host Mapping Table.
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Step 3 |
To add a host mapping, click Add and configure the following:
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Step 4 |
Click Apply. The settings are saved to the Running Configuration file. |