Reset custom DNS Servers on vNet back to default (Azure-provided)

[wordlessitguy]

When creating or updating a vnet using Azure CLI you can set DNS servers (using --dns-servers command) - however there does not appear to be a way to reset this back to the Azure-provided DNS using the Azure CLI (other than using a generic update argument to remove dhcpOptions?).

This is possible on a network interface -

`
Command
az network nic update : Update a network interface.

Arguments
--accelerated-networking : Enable accelerated networking. Allowed values: false, true.
--ip-forwarding : Enable IP forwarding. Allowed values: false, true.
--network-security-group : Name or ID of the associated network security group.
--no-wait : Do not wait for the long-running operation to finish.

DNS Arguments
--dns-servers : Space-separated list of DNS server IP addresses. Use ""('""' in
PowerShell) to revert to default Azure servers.
`

Solution -

Use same solution as above for a vnet (--dns-servers ""('""') or add flag (--az-provideddns) to reset DNS back to Azure provided DNS.

Additional note - update the DNS arguments note or documentation on how to revert when using bash?

[wordlessitguy]

Found workaround - can instead pass '' and this has the impact of nulling the DNS server list and Azure provided being used instead.

i.e -

az network vnet update --name <name> --resource-group <rgroup> --dns-servers ''

{
"addressSpace": {
"addressPrefixes": [
"10.0.0.0/8"
]
},
"bgpCommunities": null,
"ddosProtectionPlan": null,
"dhcpOptions": {
"dnsServers": []
},

Suggest documentation gets updated to reflect this behaviour and\or help comment on command instead?

[yonzhan]

network