CISSP PRACTICE QUESTIONS – 20220130

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Effective CISSP Questions

You are conducting penetration testing against a web server with a physical address, 00-15-5D-24-36-DF, configured as a dual-stack of IPv4 and IPv6. Which of the following is the most likely IP address you use to get started your testing? (Wentz QOTD)
A. 2001:db8::1
B. 169.254.1.1
C. 2001:db8:2:8d:a5:52f5
D. fe80::215:5dff:fe24:36df%10


Kindly be reminded that the suggested answer is for your reference only. It doesn’t matter whether you have the right or wrong answer. What really matters is your reasoning process and justifications.

My suggested answer is A. 2001:db8::1.

Wentz’s book, The Effective CISSP: Security and Risk Management, helps CISSP and CISM aspirants build a solid conceptual security model. It is a tutorial for information security and a supplement to the official study guides for the CISSP and CISM exams and an informative reference for security professionals.

Comparison of IPv6 and IPv4 Address Scheme
Comparison of IPv6 and IPv4 Address Scheme (Source: The FCC)

A valid IPv6 address has 128 bits or 16 hextets. 2001:db8::1 is a valid IPv6 Global Unicast address (similar to an IPv4 public IP address) with omitted leading zeros using double colons (::), while 2001:db8:2:8d:a5:52f5 is an invalid IPv6 address because it has only 6 hextets.

IPv6 Addresses
IPv6 Addresses

169.254.1.1 and fe80::215:5dff:fe24:36df%10 are so-called link-local addresses, aka AIPIA addresses; they are not routable.

IPv4 Addresses
IPv4 Addresses

Link-local addresses are also known as automatic private IP addressing (APIPA) or auto-IP. “APIPA stands for Automatic Private IP Addressing (APIPA). It is a feature or characteristic in operating systems (eg. Windows) which enables computers to self-configure an IP address and subnet mask automatically when their DHCP(Dynamic Host Configuration Protocol) server isn’t reachable. The IP address range for APIPA is (169.254.0.1 to 169.254.255.254) having 65, 534 usable IP addresses, with the subnet mask of 255.255.0.0.” (GeeksForGeeks)

In computer networking, a link-local address is a network address that is valid only for communications within the network segment or the broadcast domain that the host is connected to. Link-local addresses are most often assigned automatically with a process known as stateless address autoconfiguration or link-local address autoconfiguration, also known as automatic private IP addressing (APIPA) or auto-IP.

Link-local addresses are not guaranteed to be unique beyond their network segment. Therefore, routers do not forward packets with link-local source or destination addresses.

IPv4 link-local addresses are assigned from address block 169.254.0.0/16 (169.254.0.0 through 169.254.255.255). In IPv6, they are assigned from the block fe80::/10.

Source: Wikipedia

In IPv6, each physical interface has a unique link-local address. A scope index, e.g., %10, can be appended to a link-local address. For example, fe80::215:5dff:fe24:36df is an IPv6 link-local address generated using the EUI-64 scheme that employs the physical or media access address, 00-15-5D-24-36-DF. However, Microsoft Windows by default uses a random value for generating IPv6 Link-Local Addresses.

EUI64
IPv6 EUI-64 Bit Address (Source: Wikipedia)

Reference

您正在對物理地址為 00-15-5D-24-36-DF 且配置為 IPv4 和 IPv6 雙棧的 Web 服務器進行滲透測試。 以下哪個 IP 地址最有可能是您開始測試時使用的 IP 地址？ (Wentz QOTD)
A. 2001:db8::1
B. 169.254.1.1
C. 2001:db8:2:8d:a5:52f5
D. fe80::215:5dff:fe24:36df%10

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