Interview Q&A / Computer Networks
Computer Networks interview questions
What happens when you open a website, TCP vs UDP, DNS and HTTP.
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- What is DNS cache poisoning, and how is it prevented?
An attacker tricks a resolver into caching a forged answer, such as a bank's name mapped to the attacker's IP. Later users of that resolver are sent to the fake site. Defences include random source ports and query IDs, and DNSSEC, which signs records.
AdvancedQuick answer1 min read - Why can you not put a CNAME record on the root domain, such as example.com?
A CNAME means this name is an alias for another name, so no other record may exist at it. The root of a zone must also hold NS and SOA records, so a CNAME there would conflict. Providers offer ALIAS, ANAME or CNAME flattening as a workaround.
AdvancedQuick answer1 min read