A network administrator is manually configuring a static global unicast IPv6 address on a core server interface. The administrator enters the address string `2001:db8:100:0::45::1/64` into the operating system interface configuration file. Upon applying the configuration, the system rejects the input with a syntax error. Which of the following technical explanations identifies why this IPv6 address representation is invalid?
- The double-colon shorthand notation (`::`) is included twice in a single address string, which prevents the parser from unambiguously calculating the total number of 16-bit zero blocks represented by each occurrence.Answer
- BThe address attempts to mix explicit single-zero hexadecimal fields (`:0:`) with double-colon shorthand (`::`), which violates standard address syntax standards.
- CZero compression shorthand (`::`) is restricted exclusively to link-local address prefixes (`fe80::/10`) and cannot be applied to global unicast addresses.
- DZero compression notation was applied across the prefix boundary, which invalidates the subnet prefix length defined by the trailing `/64`.
Answer
The double-colon shorthand notation (`::`) is included twice in a single address string, which prevents the parser from unambiguously calculating the total number of 16-bit zero blocks represented by each occurrence.
The double-colon (`::`) zero compression rule allows shortening contiguous 16-bit fields of zeros. However, using `::` more than once in a single address string makes it mathematically impossible to determine how many 16-bit zero blocks each `::` replaces, leading to syntax rejection by network operating systems.
Step-by-Step Solution
Key Concept
IPv6 Address Zero Compression Rules