Validate IPv4 and IPv6 Address | Dataford Interview Questions

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Problem

At Meta, systems such as network-facing services and internal traffic filters need strict IP parsing. Implement a function that takes a string and returns whether it is a valid IPv4 address, valid IPv6 address, or Neither.

Formal Specification

Write a function validate_ip(address) that accepts a string address and returns one of:

"IPv4" if the string is a valid IPv4 address
"IPv6" if the string is a valid IPv6 address
"Neither" otherwise

A valid IPv4 address has exactly 4 decimal parts separated by .. Each part must contain only digits, be in the range 0 to 255, and must not contain leading zeros unless the part is exactly "0".

A valid IPv6 address has exactly 8 parts separated by :. Each part must be 1 to 4 characters long and contain only hexadecimal characters: 0-9, a-f, or A-F.

Constraints

1 <= len(address) <= 100
IPv4 validation requires exactly 4 segments separated by '.'
Each IPv4 segment must be a decimal number in [0, 255] with no leading zeros unless the segment is exactly '0'
IPv6 validation requires exactly 8 groups separated by ':'
Each IPv6 group must contain 1 to 4 hexadecimal characters
Do not use built-in IP parsing libraries

Function Signature

def validate_ip(address):