Aviatrix Gateways use a well-known public DNS server for their hostname
resolutions. This is to ensure the gateways can access services such as AWS SQS
to retrieve messages from the Aviatrix Controller regardless of the underlying
connectivity. Even if a VPC is set up with private DNS via its DHCP options for
EC2 instances, Aviatrix gateways still rely on the public DNS for their own
hostname resolutions.
However, Aviatrix also provides the option to use the Cloud VPC/VNet private DNS
Server. Enabling this instructs the gateway to use the VPC/VNet DNS configured
via DHCP options, replacing the Aviatrix default DNS server.
When enabled, the Controller checks if the gateway can reach the configured
VPC/VNet DNS server; otherwise, it returns an error.
This is useful when Aviatrix gateways need to resolve private DNS names, such as
an on-premises log server or non-HTTP/HTTPS FQDNs with Egress Legacy features.
For instance, if you enable
Logging
on the Aviatrix Controller, all Aviatrix Gateways forward their log information
to the configured log server. But if the log server is deployed on-premises with
a private DNS name, the Aviatrix gateway’s default DNS server cannot resolve the
domain name of the private log server. By enabling the VPC/VNet DNS server, the
gateway will start to use the VPC/VNet DNS server which should resolve the
private DNS name of the log server.
Another use case is when Aviatrix Egress Legacy FQDN on Aviatrix Controller is
enabled for non-HTTP/HTTPS FQDNs, the Aviatrix gateway must use the VPC/VNet’s
DHCP option to accurately obtain the IP address of a given hostname.
If your VPC/VNet DNS server is on-premises or only accessible over IPsec
tunnels, HA failover on Spoke gateways can cause issues. When the primary Spoke
Gateway fails over, it loses connectivity to the private DNS because the tunnel
is down and cannot re-establish until it receives AWS SQS messages from the
Controller. This results in the tunnel staying down. Using the Aviatrix Default
DNS server on the Spoke Gateway resolves this issue.
For Transit networks requiring private DNS server, ensure the DNS server
remains reachable regardless of the network tunnel status.
By default, Aviatrix gateways use the built-in Aviatrix Default DNS Server for
their own hostname resolutions. However, Aviatrix also provides the option to
use the Cloud VPC/VNet private DNS Server.
To configure the DNS server for an Aviatrix gateway:
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In Aviatrix CoPilot, go to Cloud Fabric > Gateways, click Transit
Gateways, Spoke Gateways, or Specialty Gateways tab.
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In the table, locate and click the gateway name.
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Go to the gateway’s Settings page.
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Expand the General section and locate Gateway Management DNS Server.
By default, the Aviatrix gateway uses the Aviatrix Default DNS Server. You
can choose Cloud VPC/VNet DNS Server to force the Aviatrix gateway to use a
private DNS server.