How many subnets will you get if the original IPV6 prefix is /48 and the new prefix id /56 ? O 64 O 128 O 32 256 How many subnets will you get if the original IPV6 prefıx is /56 and the new prefix id /61 ? O 128 16 O 64 O 32 None
The Correct Answer and Explanation is:
Answer:
1. From /48 to /56:
- New subnets = 2^(56 – 48) = 2^8 = 256
✅ Correct answer: 256
2. From /56 to /61:
- New subnets = 2^(61 – 56) = 2^5 = 32
✅ Correct answer: 32
Explanation
In IPv6 networking, subnets are created by extending the length of the prefix. The prefix length determines how many bits are fixed for identifying the network, and the remaining bits are used to define individual subnets or hosts.
Subnetting from /48 to /56:
- A /48 prefix means the first 48 bits of the IPv6 address are fixed.
- If we move to a /56 prefix, now the first 56 bits are fixed.
- That means 8 more bits are available for subnetting: 56 – 48 = 8 bits.
- Each bit added to the subnetting space doubles the number of possible subnets.
- So, 2^8 = 256 subnets are possible when moving from /48 to /56.
Subnetting from /56 to /61:
- A /56 prefix fixes 56 bits of the address.
- A /61 prefix fixes 61 bits.
- This gives us 5 bits (61 – 56 = 5) to create subnets.
- So, 2^5 = 32 possible subnets can be created.
This calculation uses the formula:
Number of subnets = 2^(new prefix – old prefix)
IPv6 addresses are 128 bits long, and this vast address space allows for very flexible subnetting. Commonly, organizations are allocated a /48 prefix from their ISP, and they can create up to 256 /56 subnets from that. Similarly, /56 is often used within smaller networks, and subnetting further to /61 allows for more granular allocation, like subnetting per department or device group.
Understanding how many bits are used for subnetting helps network engineers design scalable and logically segmented networks using IPv6.
