Telecommunications Software and Multimedia Laboratory

 

TML / Opinnot / T-110.301 / Assignments

in Finnish

Round 6

1. DNS (11 points)

Learning goal: To understand how a system based on distributed maintenance and authorization works.
To understand how DNS works, and to learn how to do DNS queries.

  1. Find out an IP address of the machine www.hut.fi by making a recursive query manually starting from Internet root servers. Use for example dig program and its +norecurse option (+norecursive in some environments). Pay attention to an "aa" ("Authoritative answer") flag in the flags field of dig's response. What commands did you give, which servers were you guided to and which servers gave you authoritative answers? (9 points)
  2. Why don't an IP address found by a DNS name and a DNS name found by IP address necessarily match each other in DNS? (2 points)

2. Dimensioning telephone network (3 points)

Source: the course book

Learning goal: To know that there are methods to estimate the load and quality of service caused by the network or services.

  1. The customer service center of your company has 10 lines. If each phone call is in average 5 minutes long, how many calls can be accepted during busy hour with 1% blocking probability? (2 points)
  2. You want to improve your service: accept twice more calls and halve the blocking probability. How many lines should be added to your call center to achieve this goal? (1 point)

In addition to the answer, state the formulae, conversions and substitutions you needed. You may use, for example, the calculators available on Telecom Traffic Online web pages for the final calculations.

3. Communications Market Act (6 points)

Learning goal: To know that the telecommunication market is regulated.
To familiarize yourself with the expressions used in regulations.
To get a suggestive overview of the central regulations of telecommunications field.

Sources:

Answer the following questions and justify your answers briefly, citing the relevant part of law or regulation:

  1. Based on document 35 H/2003 M: what is the difference between a telephone number which starts with 07007 and one which starts 07004?
  2. Based on 11/2004 M:
    1. Mention one method an ISP can use to reduce unsolicited e-mail ("spam").
    2. Can an ISP disconnect your machine from the network if your computer has a virus?
  3. Based on 29 C/2003 M: if you make ten calls during one hour and six of them are blocked by the telephone network, is this legal?
  4. Based on the Communications Market Act:
    1. If you have failed to pay for a television set you bought on credit, can the telephone company refuse to install a connection to you?
    2. Can a store refuse to sell you a mobile telephone if you don't subscribe to a mobile connection at the same time?

This page is maintained by the assistants of the course. Course newsgroup: opinnot.tik.tlark
The contents of the page have last been updated on 22.11.2004.
URL: http://www.tml.hut.fi/Studies/T-110.300/2004/Homeworks/round6.html