MediumCoding

Validate IP Address

Asked at

Salesforce

1Give yourself 5 minutes

2Answer out loud, not in your head

3Then compare with the answer below

Stuck? Show a way to structure it+

01Reject malformed delimiter counts first.
02Validate each IPv4 or IPv6 segment independently.
03Check leading-zero, length, range, and character rules.
04Return the matching family or neither.

Reference answer

For IPv4, split into exactly four nonempty dot-separated parts; each must contain digits only, have no leading zero unless it is 0, and parse to 0 through 255. For IPv6, split into exactly eight nonempty colon-separated groups; each has length 1 through 4 and only hexadecimal characters. Do not accept compressed IPv6 unless the specification explicitly does. The scan is O(n) time and O(1) extra space apart from split storage. Parsing with a permissive library often accepts formats the interview problem forbids.

Then expect these follow-ups

How would you support IPv6 :: compression?
Tests: protocol rules
How would you validate without allocating split arrays?
Tests: stream parsing

Hiring now

Salesforce has 1,420 open roles right now

landed applies to roles like these for you, on each company’s own site, with answers written for the role.

Get 5x interviews10 free auto-applies. No card.

Business Development Representative Belgium Market (Dutch Speaking)
Ireland - Dublin
Service Cloud Account Executive
France - Paris
Summer Intern 2027 - Content Writer
India - Bangalore

Or practice this question first

Next question