Exam AZ-700 topic 2 question 77 discussion

Why is the answer A? There is no radius option A, B, C, or D. This is a drop option for the Answer Area. It's confusing. Address Space Correct Subnet Mask Why? IPv4 /24 Maximizes number of IPv4 addresses. /24 = 256 addresses IPv6 /64 Azure requires subnets to be /64 for IPv6. /48 and /56 are too large. Quick numbers: IPv4 /24 gives 256 IPs minus Azure reserved IPs (5 reserved), so 251 usable. IPv6 /64 is standard — extremely large — Azure won't allow smaller subnet masks than /64 for IPv6.

**** Answer /25 and /64**** Vpn gw need a dedicated subnet. So two or more subnets are at least needed. You can split /24 into more subnets of /25 and /26. With the use of 2 times a /25 you have maximized the the usable IP addresses , if you use /26 subnets you have less usable IP adresses in totall Example > 251 with /24 , 246 with /25 , 236 with /26

Suggested answer is: /25 and /64 The question is asking maximize the number of usable IP addresses, which means all the subnets apart from the Gateway subnet because it can be used only from the Gateway deployment. Sine the address space for the entire VNet is /24, that will give 256 IP address which needs to be used to cover the Gateway subnet and the VMs subnets. Can't used /24 for the VMs subnets because that will take the entire IP range to the VMs subnet and then the Gateway subnet will not be able to be implemented in the VNet. So /24 is not an option. The minimum subnet can be assigned for the Gateway is /29 which will give 8 IP addresses. This will give 248 IP address which can be used for VMs subnets. To use these IP addresses (248), it needs to be created in multiple subnets starting with /25, /26, /27, /28, & /29. So the biggest subnet with usable IP addresses is /25.

to be honest this seems a weird question, at first it asks for "You need to configure the subnet masks for VNet1" and then it says "Which subnet mask should you use for each address space?" which subnet is it speaking of? Gateway, VMs or the whole Vnet one? to maximize the whole Vnet you should use /24 for IPv4 and /64 for IPv6 but for vpn gateway subnet a /26 is enough and you should subnetting the whole /24 assigned.. any ideas? Maybe I'm missing something...