Computer Networks
Tutorial #10
- What is the significance of the dot at the end of some domain
names?
- In the RR examples given in the lecture, the TTL field is set
to 86400. What is the significance of this strange number?
- What is meant by a "flat name space", and what is the alternative?
- The DNS is described as a "distributed database" of RRs.
- What does this mean?
- What is the alternative, and why is it generally regarded as
unworkable? Philosophical question: How does this alternative
compare (conceptually) with the emergence of "search engine"
sites such as Google and AltaVista for the World Wide Web?
- Most implementations of the domain name system allows
abbreviations of names so that, for example, the name
bindi
resolves to a correct address at Bendigo. How is
this handled by the nameserver? What about
bindi.bendigo
?
- Why[1] should each nameserver know
the IP address of its parent instead of the domain name of its
parent?
- What is a reverse lookup in the DNS, and why is it
regarded as a significantly harder problem than normal lookups?
- (Implementation question[2]) The
standard suggests that when a program needs to find the domain
name associated with an IP address, it should send an inverse
query to the local server first and domain
in-addr.arpa
only if that fails. Why?
[1] From Comer,
Internetworking With TCP/IP, Vol 1, 3/e P404.
[2] ibid.
See Prac #10 for the practical exercises
accompanying this tutorial.
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Copyright © 2000 by
Philip Scott,
La Trobe University.