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Zorluk: KolayCreate and Configure Virtual Networks and Subnets

Your company has an Azure subscription containing a resource group named RG1. You plan to configure a new virtual network named VNet1 in RG1. Within VNet1, you need to create a subnet named Subnet1. You plan to deploy 2727 virtual machines in Subnet1. Each virtual machine requires a dynamic private IP address from Subnet1. You must minimize the size of the subnet to conserve IP address space. Which subnet prefix is the smallest size that can support the virtual machines?

  1. /27Cevap
  2. B
    /28
  3. C
    /26
  4. D
    /29

Cevap

The prefix /27/27 is the smallest subnet size that can support the virtual machines.
The subnet prefix /27/27 is correct because it provides a total of 3232 IP addresses (232−27=322^{32-27} = 32). Since Azure reserves 55 IP addresses in every subnet (the first four and the last one), the number of usable IP addresses is 32−5=2732 - 5 = 27. This exactly matches the requirement of 2727 virtual machines, making it the smallest subnet size (highest prefix length) that can support the deployment.

Adım Adım Çözüm

1
Calculate the total number of IP addresses required for the virtual machines and Azure's system reservations.
3232 total IP addresses are required (2727 for the virtual machines + 55 reserved by Azure).
Azure reserves the first four IP addresses and the last IP address in each subnet for its own infrastructure and routing services.
2
Evaluate the total number of IP addresses provided by different CIDR prefix sizes to find the smallest subnet size that is at least 3232.
A /27/27 subnet provides 3232 IP addresses, whereas a /28/28 subnet provides 1616 IP addresses, and a /26/26 subnet provides 6464 IP addresses.
The number of IP addresses is calculated using the formula 232−prefix2^{32 - \text{prefix}}. A /27/27 prefix (232−27=322^{32-27} = 32) is the smallest prefix length that provides at least 3232 IP addresses.

Anahtar Kavram

Subnet IP address calculation and Azure reserved IP addresses
Tahmini Süre:1m 0s
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Create and Configure Virtual Networks and Subnets