Configuring DNS Fallback Policy

The DNS Fallback Policy table lets you configure up to two DNS fallback policies, each for a different traffic type - IPv4 and IPv6. The policy defines a DNS fallback sequence (priority), specifying which DNS server to use if a DNS server fails (unreachable). This table allows you to fully customize the DNS fallback sequence.

Each DNS Fallback policy allows you to prioritize (rule) the sequence ("chain") of DNS fallback between the following DNS servers:

■ DNS server configured for the OAM IPv4 interface in the IP Interfaces table (see Configuring IP Network Interfaces).
■ DNS server configured for the OAM IPv6 interface in the IP Interfaces table (see Configuring IP Network Interfaces).
■ Device's Default IPv4 DNS servers, configured in Configuring Default DNS Servers.
■ Device's Default IPv6 DNS servers, configured in Configuring Default DNS Servers.
● If you don't configure the DNS Fallback Policy table for a specific traffic type, the device's default DNS fallback sequence is applied, as described in Device's Default DNS Fallback Sequence.
● Currently, the DNS fallback Policy can't be configured per IP Interface; only to the IPv4 and IPv6 OAM interfaces.
● If the device is restored to factory defaults, the DNS Fallback Policy table doesn’t return to default, but maintains its current configuration.

The following procedure describes how to configure DNS fallback policies through the Web interface. You can also configure it through ini file [DnsFallbackPolicy] or CLI (configure network > dns-fallback-policy).

➢ To configure a DNS fallback policy:
1. Open the DNS Fallback Policy table (Setup menu > IP Network tab > DNS folder > DNS Fallback Policy).
2. Select either the IPv4 or IPv6 pre-configured row, depending on the traffic type for which you want to configure a DNS Fallback policy, and then click Edit; the following dialog box appears (e.g., for IPv4 traffic):

3. Configure a DNS Fallback policy according to the parameters described in the table below.
4. Click Apply.

DNS Fallback Policy Table Parameter Description

Parameter

Description

'Index'

(Read-only) Index number of the table row.

'Type'

type

[Type]

Defines the type of traffic (IP version) for which you want to apply the DNS Fallback policy.

■ [0] IPv4 (Default)
■ [1] IPv6

'Rule1'

rule1

[Rule1]

Defines the first DNS fallback rule.

■ [0] None (Default)
■ [1] OAM Interface IPv4
■ [2] OAM Interface IPv6
■ [3] Global DNS IPv4
■ [4] Global DNS IPv6

'Rule2'

rule2

[Rule2]

Defines the second DNS fallback rule if rule 1 fails (or configured to None).

■ [0] None (Default)
■ [1] OAM Interface IPv4
■ [2] OAM Interface IPv6
■ [3] Global DNS IPv4
■ [4] Global DNS IPv6

'Rule3'

rule3

[Rule3]

Defines the third DNS fallback rule if rule 2 fails (or configured to None).

■ [0] None (Default)
■ [1] OAM Interface IPv4
■ [2] OAM Interface IPv6
■ [3] Global DNS IPv4
■ [4] Global DNS IPv6

'Rule4'

rule4

[Rule4]

Defines the fourth DNS fallback rule if rule 3 fails (or configured to None).

■ [0] None (Default)
■ [1] OAM Interface IPv4
■ [2] OAM Interface IPv6
■ [3] Global DNS IPv4
■ [4] Global DNS IPv6