Explanation:

In Azure Virtual Networks (VNets), each subnet defines a range of IP addresses using CIDR (Classless Inter- Domain Routing) notation. The subnet mask determines how many IP addresses are available, but Azure reserves five addresses in every subnet for its internal operations.
Given the subnet range 172.16.10.0/25, the total number of IP addresses in the subnet can be calculated as follows:
A /25 subnet provides 128 IP addresses (2^(32-25) = 128).
Azure automatically reserves five IP addresses in each subnet:
The first address (172.16.10.0) is the network identifier.
The second through fourth addresses are reserved by Azure for default gateway and internal operations.
The last address (172.16.10.127) is the broadcast address.
That leaves 128 - 5 = 123 usable IP addresses for Azure virtual machines and other resources such as NICs, load balancers, or network interfaces.
This calculation and reservation rule are explicitly documented in the Microsoft Azure Virtual Network subnet documentation. Therefore, the maximum number of virtual machines (each using a single private IP address) that can connect to the subnet is 123.

Azure virtual machines can occasionally be subject to platform maintenance events. Maintenance can be planned (with notice) or unplanned. Planned maintenance includes updates to the host operating system or hardware that may require moving your VM to another host.
When you receive a maintenance notification, Azure provides options to move your VM proactively to minimize downtime. According to the Microsoft Azure Administrator documentation, the correct action is to use the "Redeploy" option or "Move VM to another host" from the Azure portal. This operation shuts down the VM, migrates it to a new physical node within the same region, and then restarts it - effectively resolving maintenance impact.
The Update management blade, however, is part of Azure Automation Update Management, which is used to schedule and manage operating system updates (Windows or Linux) across Azure and hybrid environments.
Enabling Update Management simply connects the VM to a Log Analytics workspace and does not move or redeploy the VM.
Therefore, enabling Update Management does not achieve the goal of moving VM1 to a different host to avoid maintenance. The correct action would be:
Navigate to VM1 # Help # Redeploy + reapply # Redeploy.
This redeploys the VM to another host server while retaining its network and disk configurations.
Thus, the proposed solution does not meet the goal.

No, this does not meet the goal. Assigning a built-in policy definition to the subscription is not enough to ensure that when an NSG is created, it automatically blocks TCP port 8080 between the virtual networks. This is because there is no built-in policy definition that matches this requirement. The closest built-in policy definition is "Network security groups should not allow unrestricted inbound traffic on well-known ports", but this policy only blocks TCP port 80 and 443, not 80801.
To meet the goal, you need to create a custom policy definition that enforces a default security rule for NSGs. A policy definition is a set of rules and actions that Azure performs when evaluating your resources2.
You can use a policy definition to specify the required properties and values for NSGs, such as the direction, protocol, source, destination, and port of the security rule. You can then assign the policy definition to the subscription scope, so that it applies to all the resource groups and virtual networks in the subscription.

Explanation:
IP address: You should use 10.0.1.3 as the IP address for DC1. This is because DC1 needs to have a static IP address within the subnet range of VNET1, which is 10.0.1.0/241. You cannot use 10.0.2.1 or 192.168.2.1, as they are outside of the subnet range of VNET1. You also cannot obtain an IP address automatically, as this may cause DC1 to lose its IP address and break the DNS resolution for the domain members2.
Name Resolution: You should configure VNET1 to use a custom DNS server that points to the IP address of DC1, which is 10.0.1.33. This is because DC1 is the domain controller and DNS server for contoso.com, and it needs to resolve the AD DS DNS names for the domain members that are in Azure or on-premises. You cannot use the default Azure-provided DNS server, as it does not support AD DS DNS names. You also do not need to create an Azure Private DNS zone or an Azure public DNS zone named contoso.com, as these are not required for AD DS DNS resolution.