7. Translate these passages in writing:

a) Every time you use a domain name, you use the Internet's DNS servers to translate the human-readable domain name into the machine-readable IP address.

b) One of the keys to making this work is redundancy. There are multiple DNS servers at every level, so that if one fails, there are others to handle the requests. The other key is caching. Once a DNS server resolves a request, it caches the IP address it receives.

c) Even though it is totally invisible, DNS servers handle billions of requests every day and they are essential to the Internet's smooth functioning. The fact that this distributed database works so well and so invisibly day in and day out is a testimony to the design.

8. Answer the following questions using the information from the seventh part of text 2.

1. What do we use when we use the Web or send an e-mail message? 2. What translates the human-readable domain name into the machine-readable IP address? 3. How are the top-level domain names also called? 4. How do we call the left-most word, like www? What is its function? 5. What four things can the DNS server do when a request comes in? 6. What do the root servers know? 7. What are the keys to making this work? 8. How many requests do DNS servers handle every day?

9. Look through the seventh part of text 2 once more and mark the statements as true (t) or false (f).

1.	□	Every time we use a domain name, we use the Internet`s DNS servers to translate the human-readable domain name into the machine-readable IP address.
2.	□	The list of second-level domain names include .COM, .ORG, .NET, .EDU and .GOV.
3.	□	It is not essential for every name in the .COM top-level domain to be unique.
4.	□	DNS servers accept requests to convert domain names into IP addresses.
5.	□	The DNS server can return an error message if the requested domain name is invalid or doesn`t exist.
6.	□	A DNS server would start its search for an IP address by contacting one of the minor DNS servers.
7.	□	There is only one single DNS server at every level, so that if it fails, there is no other to handle the requests.
8.	□	Caching helps to keep things from bogging down.

10. Match each top-level domain name with the type of organization it denotes.

1.	.aero	a.	Professional workers
2.	.biz	b.	Cooperatives
3.	.com	c.	Nonprofit organization
4.	.coop	d.	Museums
5.	.edu	e.	Businesses
6.	.gov	f.	International organization
7.	.info	g.	Individuals
8.	.int	h.	Commercial
9.	.mil	i.	Unrestricted use
10.	.museum	j.	United States military
11.	.name	k.	Nonmilitary agency, United States federal government
12.	.net	l.	Educational
13.	.org	m.	Air-transport industry
14.	.pro	n.	Network provider