Validate IP Address
A medium-tier problem at 28% community acceptance, tagged with String. Reported in interviews at X and 8 others.
Validate IP Address is a medium-difficulty string problem that shows up in live assessments at Apple, Nvidia, Cisco, and ServiceNow. The acceptance rate sits at 28%, which means most candidates either miss edge cases or build the validation logic wrong. You'll get a string and need to determine if it's a valid IPv4 address, a valid IPv6 address, or neither. The trick isn't complicated, but the devil is in the details: IPv4 has stricter rules around leading zeros and range boundaries, IPv6 uses hex characters and colons in a specific pattern. If this problem hits your live OA and the format validation trips you up, StealthCoder surfaces a working solution in seconds.
Companies that ask "Validate IP Address"
Validate IP Address is the kind of problem that decides whether you pass. StealthCoder reads the problem on screen and surfaces a working solution in under 2 seconds. Invisible to screen share. The proctor sees nothing. Built by an Amazon engineer who realized the OA tests how well you memorized 200 problems, not how well you code.
Get StealthCoderThe naive approach is to just split by colons or dots and check if the parts look right. That fails immediately on leading zeros, octal notation, and scope violations. IPv4 needs exactly four decimal parts between 0-255 with no leading zeros (except '0' itself). IPv6 needs exactly eight hex groups separated by colons, each group 1 to 4 characters. The real work is building the validation functions carefully, then routing the input to the correct one based on format hints. Most candidates write sloppy regex or incomplete range checks, then discover mid-interview that they've broken a dozen test cases. The structure is straightforward once you see it, but execution matters. StealthCoder is the hedge if the format parsing logic bogs you down during screen share.
Pattern tags
You know the problem.
Make sure you actually pass it.
Validate IP Address recycles across companies for a reason. It's medium-tier, and most candidates blank under the timer. StealthCoder is the hedge: an AI overlay invisible during screen share. It reads the problem and surfaces a working solution in under 2 seconds. Built by an Amazon engineer who realized the OA tests how well you memorized 200 problems, not how well you code. Works on HackerRank, CodeSignal, CoderPad, and Karat.
Validate IP Address interview FAQ
Why is the acceptance rate so low on this one?+
Edge cases with leading zeros, IPv6 hex bounds, and mixed format handling trip up most candidates. A 27% acceptance rate tells you most people code a first pass that handles happy paths, then fail validation tests. The problem is harder in execution than in concept.
Will I actually see this at a big tech company?+
Yes. It's been asked at Apple, Nvidia, Cisco, and ServiceNow. It's a real OA problem, not theoretical. The companies asking it tend to care about careful string parsing and edge case handling.
What's the trick I'm missing?+
There's no single trick. The problem is about systematic validation: build separate IPv4 and IPv6 checkers with correct range and format rules, then dispatch to the right one. Most candidates skip the systematic part and patch holes mid-code.
How much time should I spend on this in an interview?+
Plan to spend 20-25 minutes coding and testing. The logic is clear, but you need time to trace edge cases like '192.168.01.1' or '::1'. Rushing through leads to off-by-one or range bugs that blow your score.
Does this require regex or just string methods?+
String methods and basic parsing are enough. Regex can work but often introduces bugs on boundary cases. Split, loop, and validate is clearer and easier to debug live.
Want the actual problem statement? View "Validate IP Address" on LeetCode →