No DNS resolution? As for the link shortener infrastructure, I'd ask for more context to get a better idea of the scope. If there is not more context than that

No DNS resolution? As for the link shortener infrastructure, I'd ask for more context to get a better idea of the scope. If there is not more context than that, define the scope at which you're operating (eg, "I understand 'infrastructure' as 'the structure of the service' and not as 'the physical infrastructure'" and define yourself what the URL shortener does (going with "a web service with a single endpoint" sounds reasonable to me). It's really important to understand what you're trying to achieve first, especially when faced with a real problem.