Are Azure public IPs truly static or can they change?
I have 2 load balancers each have 2 VMs behind them.
I offer a multi-tenant SAAS solution to my end users and ask that they map a CNAME record in their DNS to our domain name. www.ourDomain.com
There are some scenarios where i would allow the end user to map an A record to our IPs. How risky is this with Azure IPs?
In fact, whatever basic or standard load balancer you are using, both are supporting to assign the public-facing load balancing solution with the static allocation method.
For basic SKU LB, you can change the basic public IP from the dynamic allocation method to static, for standard SKU LB, Azure always uses static allocation method for your standard public IP.
So there is no risk unless you are assigning the public IP to other resources or release these public IPs. For more details, you can look at this.
Static addresses are only released if a network interface is deleted.
If you change the allocation method to dynamic, Azure dynamically
assigns the previously assigned static IP address as the dynamic
address, even if the address isn't the next available address in the
subnet's address range. The address also changes if the network
interface is assigned to a different subnet within the same virtual
network, but to assign the network interface to a different subnet,
you must first change the allocation method from static to dynamic.
Once you've assigned the network interface to a different subnet, you
can change the allocation method back to static, and assign an IP
address from the new subnet's address range.
If you change the setting to static ip in the load balancer , it should remain static until you change it again.
Related
When creating a Public IP Adress in Azure i can choose the Tier between Regional and Global.
We are using the IP Adress for Azure Application Gateway Standard_V2. When i want to use a Global Public IP for it's Frontend i get an error that only Regional IPs are supported. I get that Azure Application Gateway is a regional Load Balancer that can't balance load between regions and routes only to Backends in a single region.
I don't understand the consequences of choosing the Tier for the Public IP tough.
Here i read that
Public IP addresses are associated with a single region. The Global
tier spans an IP address across multiple regions. Global tier is
required for the frontends of cross-region load balancers.
But does that mean, that the IP Address is only reachable from clients within a certain region? We will create a DNS Entry pointing to this IP Address which will be available globally. Or is this region just refering to where the Azure Resource is created?
Markus Strobl: I did couple of testing and identified below things.
Irrespective of type of tier selected for the Public IP address while creating, you can associate it to Azure Resources which are located in same Location as that of the Public IP
Irrespective of type of tier selected for the Public IP address while creating, these IPs can be reached from any location (post allocating them to Azure Resources)
If you want enable Cross-region load balancing, then the Public IP has to be created under Global Tier.
I was following this article - Azure virtual machine scale set agents. Everything is good and I am able to run my custom images to perform builds and deployments.
One thing that is missing there - what if agent needs to access some IP restricted resource? Previously (with a simple VM running as agent) it was easy to whitelist public IP of a given agent. With those scale sets (and --load-balancer "") I am not sure how to get them to use a static IP (preferably only 1 outgoing public IP for all VMs in a set)
Any suggestions?
When you use a Load Balancer in front of the VMSS with only one static public IP address, then all the VMSS instances only can access outside through that one static public IP address. It's easy to achieve it, you just need to configure the public IP address as static. Then you put that public IP address in the whitelist for the restricted resource.
In this way, all the instances access the restricted resource via the static public IP address and it's in the whitelist.
Whats the strategy for IP address when setting up ILB? It makes sense to have a static IP but when would you want Dynamic?
When you create an internal load balancer on Azure, you will associate a virtual network and subnet with this load balancer. If you do not know which specific IP address you will use it as the frontend IP of the load balancer, you can choose Dynamic, then Azure will assign the next available unassigned or unreserved IP address in the associated subnet's address range. Also, you can change it to static after you have created your load balancer. If you want to specify a dedicated or known IP in the subnet at the first time, you could select IP address assignment static.
Read more about Private IP addresses.
Bottom-Line.
If you have an Azure environment behind a load balance you might want Frontend IP to be static so you are rest assured that you environment's public IP will not accidentally change except you want it to, especially if you are making use of SNAT.
Also you do not really save by making it dynamic, if there is a resource behind it you will have an IP charge for the whole month.
In which scenario can we use a dynamic public IP Address ? I cannot think of a scenario where i would want to expose a public IP for internet facing azure services but that could be dynamic.
The two scenarios we use dynamic IPs are
A VM has a mechanism to auto update a DNS A record with its new address.
The Ip address has a CNAME mapped to the DNS name - so mapping www.example.com to example.westus2.cloudapp.azure.com This way whenever the address changes it still points to the same thing.
Remember though that a dynamic IP address doesn't change unless the VM is deallocated. Or the underlying host fails and VM is started on another host.
Hope this helps- https://learn.microsoft.com/en-us/azure/virtual-network/virtual-network-ip-addresses-overview-arm
That outlines the use cases for both static and dynamic IPs.
The main use case for dynamic PIP's for me is for gateways. For web or app services I would use static.
I have an Azure VM with SQL Server on. There are a number of applications using this database via it's public ip address. The ip address is currently set to Dynamic and the VM requires maintenance which could change it. Is there a way of assigning a static ip address to the VM while keeping the current one active while I update the applications to use the new static one?
Is there a way of assigning a static ip address to the VM while
keeping the current one active while I update the applications to use
the new static one?
If I understand it correctly, you just want to change the public IP address to static.
We can change the public IP address to static via Azure portal, that IP address will not change.