75 lines
4.5 KiB
ReStructuredText
75 lines
4.5 KiB
ReStructuredText
Keep DNS Nameserver Order Consistency In Neutron
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================================================
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In Neutron subnets, DNS nameservers are given priority when created or updated.
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This means if you create a subnet with multiple DNS servers, the order will
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be retained and guests will receive the DNS servers in the order you
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created them in when the subnet was created. The same thing applies for update
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operations on subnets to add, remove, or update DNS servers.
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Get Subnet Details Info
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-----------------------
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::
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changzhi@stack:~/devstack$ neutron subnet-list
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+--------------------------------------+------+-------------+--------------------------------------------+
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| id | name | cidr | allocation_pools |
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+--------------------------------------+------+-------------+--------------------------------------------+
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| 1a2d261b-b233-3ab9-902e-88576a82afa6 | | 10.0.0.0/24 | {"start": "10.0.0.2", "end": "10.0.0.254"} |
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+--------------------------------------+------+-------------+--------------------------------------------+
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changzhi@stack:~/devstack$ neutron subnet-show 1a2d261b-b233-3ab9-902e-88576a82afa6
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+------------------+--------------------------------------------+
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| Field | Value |
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+------------------+--------------------------------------------+
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| allocation_pools | {"start": "10.0.0.2", "end": "10.0.0.254"} |
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| cidr | 10.0.0.0/24 |
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| dns_nameservers | 1.1.1.1 |
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| | 2.2.2.2 |
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| | 3.3.3.3 |
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| enable_dhcp | True |
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| gateway_ip | 10.0.0.1 |
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| host_routes | |
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| id | 1a2d26fb-b733-4ab3-992e-88554a87afa6 |
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| ip_version | 4 |
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| name | |
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| network_id | a404518c-800d-2353-9193-57dbb42ac5ee |
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| tenant_id | 3868290ab10f417390acbb754160dbb2 |
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+------------------+--------------------------------------------+
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Update Subnet DNS Nameservers
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-----------------------------
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::
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neutron subnet-update 1a2d261b-b233-3ab9-902e-88576a82afa6 \
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--dns_nameservers list=true 3.3.3.3 2.2.2.2 1.1.1.1
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changzhi@stack:~/devstack$ neutron subnet-show 1a2d261b-b233-3ab9-902e-88576a82afa6
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+------------------+--------------------------------------------+
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| Field | Value |
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+------------------+--------------------------------------------+
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| allocation_pools | {"start": "10.0.0.2", "end": "10.0.0.254"} |
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| cidr | 10.0.0.0/24 |
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| dns_nameservers | 3.3.3.3 |
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| | 2.2.2.2 |
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| | 1.1.1.1 |
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| enable_dhcp | True |
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| gateway_ip | 10.0.0.1 |
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| host_routes | |
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| id | 1a2d26fb-b733-4ab3-992e-88554a87afa6 |
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| ip_version | 4 |
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| name | |
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| network_id | a404518c-800d-2353-9193-57dbb42ac5ee |
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| tenant_id | 3868290ab10f417390acbb754160dbb2 |
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+------------------+--------------------------------------------+
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As shown in above output, the order of the DNS nameservers has been updated.
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New virtual machines deployed to this subnet will receive the DNS nameservers
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in this new priority order. Existing virtual machines that have already been
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deployed will not be immediately affected by changing the DNS nameserver order
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on the neutron subnet. Virtual machines that are configured to get their IP
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address via DHCP will detect the DNS nameserver order change
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when their DHCP lease expires or when the virtual machine is restarted.
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Existing virtual machines configured with a static IP address will never
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detect the updated DNS nameserver order.
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