# 70-649: Configuring Network Access

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These questions are based on 70-649 – TS.

Objective: Configuring Network Access
Sub-Objective: Configure IPv4 and IPv6 Addressing

You are the network administrator for your company. The company network consists of Windows Server 2008 server computers and Windows Vista client computers. You have the following eight Internet Protocol version 6 (IPv6) subnetted address prefixes:

1. 3FFE:FFFF:0:C000::/54
2. 3FFE:FFFF:0:C400::/54
3. 3FFE:FFFF:0:C800::/54
4. 3FFE:FFFF:0:CC00::/54
5. 3FFE:FFFF:0:D000::/54
6. 3FFE:FFFF:0:D400::/54
7. 3FFE:FFFF:0:D800::/54
8. 3FFE:FFFF:0:DC00::/54

What would be the original prefix length for the global address prefix 3FFE:FFFF:0:C000::?

1. 51
2. 52
3. 53
4. 54

1. 51

Tutorial:
The original prefix length for the global address prefix 3FFE:FFFF:0:C000:: is 51. The eight IPv6 subnetted address prefixes are the result of 3-bit subnetting of the global address prefix 3FFE:FFFF:0:C000::/51. To perform 3-bit subnetting of the global address prefix 3FFE:FFFF:0:C000::/51, you must use the following calculations:

Hexadecimal value of the subnet ID being subnetted, F = 0xC000

Subnetting bits, s = 3

Network bits, m = 51

Number of bits within the subnet ID that are already fixed, f = 51 – 48 = 3

Number of prefixes, n = 2^3 = 8

Incremental value between each successive subnet ID expressed in hexadecimal, i = 2^16 – (f + s)

i = 2^16 – (3 + 3) = 1024 = 0 x 400

New prefix length, P = 51 + 3 = 54

All other options are incorrect.

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