Port Address Translation (PAT) is an extension of Network Address Translation (NAT) that permits multiple devices on a LAN to be mapped to a single public IP address to conserve IP addresses.

What better way than reserving IPv4 address space than not use it at all by using IPv6. I think its A & B.

A & B are correct IPv6 has much larger addresses. Network Address Translation (NAT) allows the use of private IP networks.

ARIN’s free pool of IPv4 address space was depleted on 24 September 2015. As a result, we no longer can fulfill requests for IPv4 addresses unless you meet certain policy

AB are correct

BC are the best options

I'm going for A+B Pure IPV6 doesn't use v4 address PAT is an extension of NAT, so that with private addresses conserve IPv4 E would be an acceptable answer if it was paired with PAT/NAT , but it does not specify like it does in B. This means that they will not be able to access the interne, and that was a part of the question.

For those saying E, "Custom addresses from ARIN" is an option you maybe read it in theory somewhere, but in practice, anyone that has ever worked in a Service Provider in the last decade knows that it is IMPOSSIBLE to get addresses from ARIN. So no, E is not an option AT ALL in the real world.

This is from official book : The Internet community worked hard during the 1990s to solve this problem, coming up with several solutions, including the following: ■ A new version of IP (IPv6), with much larger addresses (128 bit) ■ Assigning a subset of a public IP network to each company, instead of an entire public IP network, to reduce waste, using a feature called “Classless Interdomain Routing” (CIDR) ■ Network Address Translation (NAT), which allows the use of private IP networks So A, B and E are correct. I think the question is wrong.

SO guys what would be the correct answer for the exam ??

I would say AB

E) custom ARIN addresses are not Public IP addresses (or are they?), so this answer is still viable

The two IP addressing schemes that provide internet access to users on the network while preserving the public IPv4 address space are: B. PAT with private internal addressing: This approach uses Network Address Translation (NAT) to translate the private internal IP addresses of devices on the network to a single public IP address when accessing the Internet. This allows many devices to share a single public IP address, preserving the public IPv4 address space. E. Custom addresses from ARIN: Organizations can request their own unique address space from the American Registry for Internet Numbers (ARIN) to use on their internal networks. This address space can be used in combination with NAT to provide Internet access to users on the network while preserving public IPv4 address space. Therefore, the correct answers are B. PAT with private internal addressing and E. Custom addresses from ARIN.

A & B are correct

AB are the correct answers

I would go for A and C

BE are correct