When I shutdown a VM from Azure portal, it enters de-allocated state. I understand that if a public ip address is assigned to it, the only way to ensure that it maintains that ip is by creating a static ip address.
But what happens to a (dynamic) private ip address when the VM enters deallocated state ? Does it maintain the private ip address or do I lose it ?
According to the documentation: Once assigned, dynamic IP addresses are released if a network interface is:
Deleted
Reassigned to a different subnet within the same virtual network.
The allocation method is changed to static, and a different IP address is specified.
When you shut down a VM you are not actually doing any of these 3 things. So it should keep the IP address.
The standard way that DHCP works is that an IP address has a Time-To-Live (the default in Windows was 72 hours).
So if all the IP addresses in the subnet have been used and some have expired, since they have not been renewed, due to the VM's being shut down. Then new VM's may start to use some previously assigned IP addresses.
Related
There was a virtual machine that could be connected to and there was an ip associated with this virtual machine. Now for some reason I can't connect to this virtual machine. This error comes out. I looked at the list of all virtual machines and didn't see any connected to this ip address. Could one of the employees have deleted it? Or what could have happened to it?
The IP address assigned by Azure to a Virtual Machine is dynamic in default
Selecting dynamic allocation method for an IP address resource means the IP address is not allocated at the time of the resource creation. The public IP address is allocated when you associate the public IP address with a virtual machine. The IP address is released when you stop (or delete) the resource, the IP address can be assigned to a different resource. If the IP address is assigned to a different resource while resource A is stopped, when you restart resource A, a different IP address is assigned.
If the virtual machine is stopped or rebooted, the IP address will be deallocated from the Virtual Machine. So, you would not be able to connect to the Virtual Machine with the same IP address again.
You can also check the activity log of that Resource Group to check if the VM is deleted.
After creating a VM in Azure, there is a public IP assigned to it (the IP address can be check out under Azure portal > Virtual machine > Networking).
Is this public IP address assgined by Azure static or not?
Update:
When click the Stop button, there is a warning message "Public IP address will be lost ...".
The public IP address assigned by Azure is dynamic in default. The static type needs to be set manually.
Update
About the dynamic method for the public IP address, you can see rules when the public IP address would change like this:
Selecting dynamic allocation method for a basic public IP address
resource means the IP address is not allocated at the time of the
resource creation. The public IP address is allocated when you
associate the public IP address with a virtual machine or when you
place the first virtual machine instance into the backend pool of a
basic load balancer. The IP address is released when you stop (or
delete) the resource. After being released from resource A, for
example, the IP address can be assigned to a different resource. If
the IP address is assigned to a different resource while resource A is
stopped, when you restart resource A, a different IP address is
assigned.
It is based on the settings, When you are creating a new VM, you can find Under Settings, select Public IP address.
A few days ago, the IP address of our VB Windows Server changed from 40.x.x.x to 13.x.x.x on the Azure platform. We have many loggers in the field that connect to this IP address and now, none of them can connect.
Can the IP change without any warning from Azure?
Also, there is no support to be found. No number, no online support... I mean, This is not a problem I should be paying support for... besides.. support is more expensive than the VM.
Your IP address will change if, for instance, you restart your virtual machine. However, you can set this to be static by doing so:
go to Public IP addresses
Click Configuration
Set assignment to Static
Click Save
This will retain the IP address that you have right now but at an additional cost.
Can the IP change without any warning from Azure?
For now, there is no warning when public IP address change. I think you should know IP address types and allocation methods in Azure.
There are two methods in which an IP address is allocated to a public IP resource - dynamic or static. The default allocation method is dynamic, where an IP address is not allocated at the time of its creation. Instead, the public IP address is allocated when you start (or create) the associated resource (like a VM or load balancer). The IP address is released when you stop (or delete) the resource. This causes the IP address to change when you stop and start a resource.
If you want to public IP address not change, you could change dynamic to static.
we need to access our partner's sql azure db, they ask for an ip so they add to the whitelist, thing is we doing the dev work on our azure vm (under different subscription), what ip should we give them, I suppose a public IP address? Will that change over time?
Thanks advance for the help!
Your VM public IP will not change unless all the VMs in that cloud service (the service holding the public IP) are stop/deallocated. Restarting the VM won't change the IP either.
I usually shutdown my VM very carefully to prevent accidentally changing my IP addresses. So far for past few years, I just tried once unintended change.
Note:
You may also consider the newly introduced Reserved IP to reserve an IP and prevent it from changing. However,
[a]t this time, you can’t reserve an IP address for a cloud service
that you have already created.
which means you could only reserve a new IP address if you would like to use Reserved IP.
We have an azure virtual network with a web role, worker role and a dedicated sql VM. Currently we're using the VM dns name in the database connection string. I was thinking it would be better to update the connection string to use the private ip address to skip the name resolution, mydbserver.cloudapp.net to 10.0.0.1.
Since all virtual machines have to use DHCP is there a chance the private ip will change? If so is there anyway to address this? Thanks
The SQL Server VM will have a persistent private IP within the Virtual Network.
From Windows Azure Virtual Network Overview:
Persistent private IP addresses: Virtual machines within a VNet will
have a stable private IP address. We assign an IP address from the
address range you specify and offer an infinite DHCP lease on it. So
the IP address will stay with the virtual machine for its lifetime.
to be extra safe, you can set a static vnet IP that guarantees that it never changes:
http://windowsitpro.com/windows-azure/set-azure-vm-static-ip-address