Exercise: Domain Name System

Scalability

• Explain the significance of Amdahl’s law for scalability.
• Which sources of execution time jitter can cause delays in HPC applications?
• What strategies can be applied to reduce or mitigate such jitter?

DNS

• What is an Internet Standard, and which document defines the DNS protocol?
• Which design strategies enable the DNS to scale?
• Demonstrate the interaction of the resolver library with the DNS servers.
  • Using dig, manually replay all name-server requests emitted by the resolver library and its primary name server when searching for an A record for the name unknown.tu-dresden.de.
  • Hint: Use the dig option +norecurse to replay search steps individually.
  • Did one of the DNS answers come from a name server's cache? If yes: How would the request-answer sequence have differed if all of the participating name server's caches would have been empty?
• Besides translating names to IP addresses, which other information is stored in DNS?