Tamilnadu State Board New Syllabus Samacheer Kalvi 12th Computer Applications Guide Pdf Chapter 12 DNS (Domain Name System) Text Book Back Questions and Answers, Notes.

## Tamilnadu Samacheer Kalvi 12th Computer Applications Solutions Chapter 12 DNS (Domain Name System)

### 12th Computer Applications Guide DNS (Domain Name System) Text Book Questions and Answers

Part I

Choose The Correct Answers
Question 1.
Which of the following is used to maintain all the directory of domain names?
a) Domain name system
b) Domain name space
c) Name space
d) IP address
Answer:
a) Domain name system

Question 2.
Which of the following notation is used to denote IPv4 addresses?
a) Binary
b) Dotted-decimal
c) Hexadecimal
d) a and b
Answer:
d) a and b

Question 3.
How many bits are used in the IPv addresses?
a) 32
b) 64
c) 128
d) 16
Answer:
c) 128

Question 4.
Expansion of URL is
a) Uniform Resource Location
b) Universal Resource Location
c) Uniform Resource Locator
d) Universal Resource Locator
Answer:
c) Uniform Resource Locator

Question 5.
How many types are available in Relative URL?
a) 2
b) 3
c) 4
d) 5
Answer:
a) 2

Question 6.
Maximum characters used in the label of a node?
a) 255
b) 128
c) 63
d) 32
Answer:
c) 63

Question 7.
In domain name, sequence of labels are separated by
a) ;
b) .(dot)
c) :
d) NULL
Answer:
b) .(dot)

Question 8.
Pick the odd one out from the following.
a) node
b) label
c) domain
d) server
Answer:
d) server

Question 9.
Which of the following initiates the mapping of the domain name to IP address?
a) Zone
b) Domain
c) Resolver
d) Name servers
Answer:
b) Domain

Question 10.
Which is the contiguous area up to which the server has access?
a) Zone
b) Domain
c) Resolver
d) Name servers
Answer:
a) Zone

Question 11.
ISP stands for
a) International Service provider
b) Internet Service Provider
c) Internet service Protocol
d) Index service provider
Answer:
b) Internet Service Provider

Question 12.
TLD stands for
a) Top Level Data
b) Top Logical Domain
c) Term Level Data
d) Top Level Domain
Answer:
d) Top Level Domain

Question 13.
Which of the following statements are true?
i) Domains name is a part of URL.
ii) URL made up of four parts
iii) The relative URL is a part of the Absolute URL
iv) URL doesn’t contain any protocol
a) i & ii
b) ii
c) i, ii & iii
d) i, ii & iv
Answer:
b) ii

Question 14.
Assertion (A): The number of addresses used in the IPv6 addressing method is 128.
Reason (R): IPv6 address is a 128-bit unique address.
a) A is true and R is false.
b) A is false and R is true.
c) Both A and R are correct and R is the correct explanation of A.
d) Both A and R are correct and R is not the correct explanation of A.
Answer:
b) A is false and R is true.

Question 15.
Match the following
a. domain – 1. The progress that initiates translation
b. zone – 2. contains a database of domain names
c. name server 3. single node
d. resolver 4. contiguous nodes
a. 1432
b. 3421
c. 3214
d. 3412
Answer:
a. 1432

Part II

Short Answers

Question 1.
List any four domain names.
Answer:
Domain Name:

1. com
2. edu
3. gov
4. mil

Meaning:

1. Commercial Organisation
2. Educational Institution
3. Government (US)
4. Military groups

Question 2.
What is an IP address?
Answer:

• Internet Protocol (IP) address is simply the logical address in the network layer.
• Like how the door number/flat number is used to 10. differentiate individual house from others in the same apartment
• IP address is also used to find the host system in the whole network.

Question 3.
What are the types of IP address?
Answer:

1. IPv4 Address
2. IPv6 Address

Question 4.
What is an URL?
Answer:

• URL (Uniform Resource Locator) is the address of a document on the Internet.
• URL is made up four parts-protocols, hostname, folder name and file name.

Question 5.
List out four URLs you know.
Answer:
URL:

1. http: //www. example.com/index, html
2. http://www.computer.com
3. http://www.ibm.com
4. https://www.hellotravel.com

Question 6.
What are the types of URLs?
Answer:
Depending on the location of the document the URL is divided into 2 types

1. Absolute URL
2. Relative URL

Question 7.
What is a domain?
Answer:

• A domain is a single node of the Domain Namespace.
• In the domain name space (DNS) tree structure domain is a sub structure tree. The domain can be further divided into sub domains.

Question 8.
What is a zone?
Answer:

• Zone is the contiguous part up to which the server has access.
• The domain assigned for the server does not divide into further subdomains the zone is the same as the domain.

Question 9.
What is a resolver?
Answer:

• Resolver is a program which is responsible for initiating the translation of a domain name into an IP address.
• A host system need to map domain name to IP address or vice versa according to the call and that work is done by resolver.

Question 10.
What are the categories available in domain name space?
Answer:
There are 3 important components in the Domain Name System. They are Namespace, Name server and Zone.

Question 11.
Write any four generic Top-Level Domain.
Answer:

 Domain Name Meaning com Commercial Organisation edu Education Institutions gov Government (US) mil Military groups

Part III

Explain In Brief Answer

Question 1.
Write a note on DNS.
Answer:

• Domain name space was designed to achieve a hierarchical namespace.
• In this, the names are represented as a tree-like structure with a root element on the top and this tree can have a maximum of 128 levels starting from the root element taking the level 0 to level 127.

Question 2.
Differentiate IPv4 and IPv6.
Answer:

 IPv4 IPv6 It has a 32-bit address length It has a 128-bit address length It Supports Manual and DHCP address configuration It supports Auto and renumbering address configuration In IPv4 end to end, connection integrity is Unachievable In IPv6, end to end connection integrity is Achievable It can generate 4.29×109 address space Address space of IPv6 is quite large it can produce 3.4×1038 address space

Question 3.
Differentiate Domain name and URL
Answer:

 URL DOMAIN NAME URL is a full web address used to locate a webpage. A domain name is the translated and simpler form of a computer’s IP address (Logical address). Complete web address containing domain name also. Part of the URL defines an organization or entity. The method, hostname (domain name), port, and path. Based on subdomains (top-level, intermediate level, low level)

Question 4.
What are the differences between Absolute URL and Relative URL?
Answer:

 Absolute URL Relative URL Absolute URL is the complete address of a document on the Inter­net. Relative URL is the par­tial address of a docu­ment on the Internet. Absolute URL contains all the information that are required to find the files on the Internet. Relative URL contains only file name or file name with folder name. If any of the four parts is missing then the browser would not able to link to the specific file We can use this type of URL when the file is on the same server related to the original document.

Question 5.
Write a note on the domain name.
Answer:

1. Domain name is the sequence of labels. In domain name the sequence of labels are separated ‘ by dot (.).
2. The domain name is always read from the lower level to higher level i.e., from the leaf node to root node.
3. Since the root node always represents NULL string, all the domain name ending with dot.

Question 6.
Differentiate web address and URL
Answer:

 WEB ADDRESS URL A Web Address more commonly defines a unique name that helps people remember a URL. A URL is the address of a particular website, an audio stream, or document available on the Web. It is like a memorable street address, can help people find you online. It is the Internet address of a particu­lar site or document available via the World Wide Web.

Part IV

Explain In Detail

Question 1.
Explain briefly the components of DNS.
Answer:

DNS Components:
There are three important components in the Domain Name System. They are:

1. Namespace
2. Name server
3. Zone

1. Name Space:

• The domain names must be very unique and appropriate. The names should be selected from a namespace.
• The name space can be organized in two ways
• Flat name space
• Hierarchical name space
• Flat name space is where the name is assigned to the IP address. They do not have any specific structure.
• Hierarchical name space is where the name is made up of several parts. The first part may represent the nature of organization, the second part may represent the name of organization, and third part may represent the department of the organization.
• Domain name space was designed to achieve hierarchical name space.

2. Name Servers:

• The information which needs to be stored in Domain name space is quite large. Single system would be inefficient to store such a huge amount as responding to requests from all over the world. It also becomes unreliable because in case of any failure the data becomes inaccessible.
• Name Server is a main part in the Domain Name System (DNS). It trAnswer:late the domain names to IP addresses.
• Name server contains the DNS database which consists of domain names and their corresponding IP addresses.
• There is a need to store large number of domain names for the world wide usage, so plenty of servers are used in the hierarchical manner.
• Name servers do the important task of searching the domain names. While you searching a website, Local Name server (provided by ISP) asks the different name servers until one of them find out your Answer. At last, it returns IP address for that domain name.

3. Zone:

• The entire namespace is divided into many different zones. It is the area up to which the server has access.
• Zone is defined as a group of contiguous domains and sub-domains. If the zone has a single domain, then the zone and domain are the same.
• Every zone has a server which contains a database called a zone file. Using the zone file, the DNS server replies the queries about hosts in its zone. There are two copies of zone files available, Master file and slave file.

Question 2.
Classify and Explain the IP address.
Answer:

• Internet Protocol (IP) address is simply the logical address in the network layer.
• Like how the door number/flat number is used to differentiate an individual house from others in the same apartment.
• An IP address is also used to find the host system in the whole network.
• Due to increase in the number of system in a network, there is a need of more addresses which lead to two addressing methods i.e., IPv4 and IPv6.

IPv4 Address

• It IPv4 address is a 32-bit unique address given to a computer system.
• No two systems can have same IP address.
• If the network has p connections then ‘ip’ addresses should be there.
• An address space is the total number of address¬es that can be made by that protocol.
• It is determined by the number of bits that the protocol used.
• If the protocol uses ‘n’ bits then the address space of that protocol would be ‘2n’ addresses can be formed. So, the number of addresses that can be formed in IPv4 is 232,
• There are two ways to represent the IP address
• Binary notation
• Dotted-decimal notation
• In binary notation the address is expressed as 32-bit binary values.
• For E.g. 00111001 10001001 111000 00000111
• In dotted-decimal notation the address is written in decimal format separated by dots(.). For e.g. 128.143.137.144

IPv6 Address

• IPv6 address is a 128-bit unique address given to a computer system.
• The number of addresses that can be formed in IPv6 is 2128. In IPv6 address, the 128 bits are divided into eight 16-bits blocks.
• Each block is then changed into 4-dig¬it Hexadecimal numbers separated by colon symbols.
• E.g. 2001:0000:32313:DFE1:0063:0000:0000:F EFB.a

Question 3.
Explain about the name server?
Answer:
Name Servers:
1. The information which needs to be stored in the Domain namespace is quite large. A single system would be inefficient and insufficient to store such a huge amount as responding to requests from all over the world. It also becomes unreliable because in case of any failure the data becomes inaccessible.

2. The solution to this problem is to distribute the information among many computers. The best way to do that is to divide the entire space into many domains and subdomains

3. DNS also allows domains to be further divided into subdomains. By this, the solution to the problem is obtained and the hierarchy of servers is also maintained.

4. Name servers store the data and provide it to clients when queried by them. Name Servers are programs that run on a physical system and store all the zone data.

5. Name Server is a main part in the Domain Name System (DNS). It translates the domain names to IP addresses.

6. Name server contains the DNS database which consists of domain names and their corresponding IP addresses.

7. There is a need to store large number of domain names for worldwide usage, so plenty of servers are used in a hierarchical manner.

8. Name servers do the important task of searching the domain names. While you searching a website, the Local Name server (provided by ISP) ask the different name servers until one of them find out your Answer. At last it returns IP address for that domain name.

Types of Name Servers
There are three types of Name Servers which control the entire Domain Name System:
(i) Root Name Server – top-level server which contains entire DNS tree, maintained by ICANN.
There are 13 servers.

(ii) Primary/Master Name Server – contains a zone resource records. These records are updatable by domain name holders such as organizations.

(iii) Secondary/Slave Name Server – contains a copy of primary server files. This server has no authority to update, but reduce the workload of master server by sharing the queries.

Question 4.
What is domain name space? Explain.
Answer:

• Domain name space was designed to achieve hierarchical name space.
• In this, the names are represented as a tree like structure with root element on the top and this tree can have a maximum of 128 levels starting from root element taking the level 0 to level 127.
• The domain namespace where the root element is present at the top most level i.e., level 0.
• The root element always represents the NULL string (empty string).
• The next level to the root element is node (children of root element). Each node in the tree has a label and a domain name.

Label:

• It is a string which can have maximum of 63 characters.
• Each node in that level should have different labels thereby assuring the individuality of the domain name.
• In other words, Labels are the names given to domains.
• Domain is a sub tree in domain name space tree structure. The domain can be further divided into sub domains.

Domain name

• It is the sequence of labels. In domain name the sequence of labels are separated by dot (.).
• The domain name is always read from the lower level to higher level i.e., from the leaf node to root node.
• Since the root node always represent NULL string, all the domain name ending with dot.

Basic rules of Domain names

• Domain can consists of Alphabets a through z, and the digits 0 through 9.
• Hyphens are allowed, but hyphens cannot be used as first character of a domain name.
• Spaces are not alloweds
• Special symbols (such as !, $, &,. not permitted. Question 5. Explain how the DNS is working. Answer: 1. When the user enters the URL (consists of a protocol, domain name, folder name, filename) in the browser, the system fist checks its DNS cache for the corresponding IP address. 2. If the IP address is found in the cache then the information is retrieved from the cache. 3. If not, then the system needs to perform a DNS query i.e., the system needs to query the resolver about the IP address from Internet Service Provider (ISP). 4. Each resolver has its own cache and if it is found in that then that information is retrieved. 5. If not, then the query is passed to the next domain server i.e., TLD (Top Level Domain) which reviews the request and directs the query to name servers associated with that specific domain. 6. Until the query is solved it is passed to next level domains. At last, the mapping and the record are returned to the resolver who checks whether the returned value is a record or an error. 7. Then the resolver returns the record back to the computer browser which is then viewed by the user. ### 12th Computer Applications Guide DNS (Domain Name System) Additional Important Questions and Answers Part A Choose The Correct Answers: Question 1. Expand DNS? (a) Direct Name Server (b) Domain Name System (c) Domain Name Security (d) Direct Name Service Answer: (b) Domain Name System Question 2. For the communication to takes place, the information should pass through …………… layers a) six b) two c) end to end d) Seven Answer: d) IP addresses Question 3. While typing a web address, DNS translates it into a machine-friendly IP address. (a) True (b) False Answer: (a) True Question 4. DNS provides the domain name to IP address mapping through …………. a) IP address b) Name Servers c) domain d) URL Answer: b) Name Servers Question 5. Paul V. Mockapetris together with ………………. invented the Internet Domain Name System (DNS). a) Jon Postel b) Dennis Ritchie c) James Gostling d) Carrelli Answer: a) Jon Postel Question 6. IP stands for ………………… (a) Input process (b) Input (c) Internet Protocol (d) Internet Power Answer: (c) Internet Protocol Question 7. ……………….. is available below the root domain. a) IANA b) IPv4 c) IPv6 d) TLD Answer: d) TLD Question 8. How many IP addressing methods are there? (a) 1 (b) 2 (c) 3 (d) 4 Answer: (b) 2 Question 9. …………. is a program running on a dedicated machine which handles the queries of www end-user. a) Webserver b) Web Host c) DNS d) HTML Answer: a) Webserver Question 10. If the protocol uses ‘n’ bits then the address space of that protocol would be ……………………. (a) n (b) n2 (c) 2n (d) 2n Answer: (d) 2n Fill in The Blanks. 1. …………… is a logical address used to uniquely identify a computer over the Network. Answer: IP address 2. IPv4 address is a …………… unique address given to a computer or a device. Answer: 32 bit 3. IPv6 address is a ……………. unique address given to a computer or a device. Answer: 128 bit 4. …………… follows Hexadecimal number notation. Answer: IPv6 5. ……………. is the address of a document on the Internet. Answer: URL (Uniform Resource Locator) 6. ……………… contains only folder name and the file name or just the file name. Answer: Relative URL 7. …………….. is a tree-like structure with a root element on the top. Answer: Domain namespace. 8. The domain name is always read from the ……………. Answer: leaf node to root node. 9. In the domain name space (DNS) tree structure …………… is a substructure tree. Answer: domain 10. …………. are programs that run on a physical system and store all the zone data. Ans : Name Servers 11. ……………….. provides to clients when queried by them. Answer: Name Servers 12. ……………. non-profit organization which regulates the Internet. Answer: ICANN 13. ………….. is an affiliated authority of ICANN. Answer: IANA (Internet Assigned Numbers Authority) 14. ……………… is a group of contiguous domains and subdomains in the Domain Name Space. Answer: Zone Assertion And Reason Question 1. Assertion (A): Domain Name System (DNS) maintains all the directory of domain names and helps us to access the websites using the domain names. Reason(R): t translates the domain name into an IP address. a) Both (A) and (R) are correct and (R) is the correct explanation of (A) b) Both (A) and (R) are correct, but (R) is not the correct explanation of (A) c) (A) is true and (R) is false d) (A) is false and (R) is true Answer: c) (A) is true and (R) is false Question 2. Assertion (A): IPv4 address is a 64-bit unique address. Reason(R): There are two ways to represent the IP address: Binary notation, Dotted-decimal notation. a) Both (A) and (R) are correct and (R) is the correct explanation of (A) b) Both (A) and (R) are correct, but (R) is not the correct explanation of (A) c) (A) is true and (R) is false d) (A) is false and (R) is true Answer: d) (A) is false and (R) is true Question 3. Assertion (A): Label is a string Reason(R): Label can have a maximum of 63 characters a) Both (A) and (R) are correct and (R) is the correct explanation of (A) b) Both (A) and (R) are correct, but (R) is not the correct explanation of (A) c) (A) is true and (R) is false d) (A) is false and (R) is true Answer: a) Both (A) and (R) are correct and (R) is the correct explanation of (A) Question 4. Assertion (A): Domain namespace is a tree-like structure with a root element on the top Reason(R); it can have a maximum of 127 levels starting from the root element a) Both (A) and (R) are correct and (R) is the correct explanation of (A) b) Both (A) and (R) are correct, but (R) is not the correct explanation of (A) c) (A) is true and (R) is false d) (A) is false and (R) is true Answer: c) (A) is true and (R) is false Question 5. Assertion (A): The Resolver is a service of ICANN Reason(R): Resolver, a client/ server application, initiates the process of resolving the domain names. a) Both (A) and (R) are correct and (R) is the correct explanation of (A) b) Both (A) and (R) are correct, but (R) is not the correct explanation of (A) c) (A) is true and (R) is false d) (A) is false and (R) is true Answer: d) (A) is false and (R) is true Question 6. Assertion (A): URL Stands for Uniform Resource Locator Reason(R): URL- the address of a specific web page or file on the Internet. a) Both (A) and (R) are correct and (R) is the correct explanation of (A) b) Both (A) and (R) are correct, but (R) is not the correct explanation of (A) c) (A) is true and (R) is false d) (A) is false and (R) is true Answer: a) Both (A) and (R) are correct and (R) is the correct explanation of (A) Question 7. Assertion (A): A web server is a program running on a dedicated machine which handles the queries of the www end user. Reason(R): A web server is a type of Web Host. a) Both (A) and (R) are correct and (R) is the correct explanation of (A) b) Both (A) and (R) are correct, but (R) is not the correct explanation of (A) c) (A) is true and (R) is false d) (A) is false and (R) is true Answer: c) (A) is true and (R) is false Find The Odd One On The Following 1. (a) File Name (b) Protocol (c) HTML (d) Host Name Answer: (c) HTML 2. (a) Label (b) Namespace (c) Name server (d) Zone Answer: (a) Label 3. (a) Flat Namespace (b) Domain Namespace (c) Host Namespace (d) Hierarchical Namespace Answer: (c) Host Namespace 4. (a) Tree Like Structure (b) 128 Levels (c) NULL string (d) Flat Namespace Answer: (d) Flat Namespace 5. (a) .com (b) -ta (c) .gov (d) .nic Answer: (b) -ta 6. (a) com (b) net (c) bd (d) info Answer: (c) bd 7. (a) India (b) Malaysia (c) Singapore (d) Srilanka Answer: (b) Malaysia 8. (a) Name server (b) DNS Database (c) IP Address (d) HTTP Answer: (d) HTTP 9. (a) Primary Name Server (b) Secondary Name Server (c) Node Name Server (d) Root Name Server Answer: (c) Node Name Server 10. (a) Host (b) Webserver (c) DNS server (d) Namespace Answer: (d) Namespace 11. (a) Name server (b) Resolver (c) ICANN (d) Zone Answer: (c) ICANN 12. (a) 32 bit (b) Binary Notation (c) Hexadecimal (d) Dotted decimal Answer: (c) Hexadecimal 13. (a) WHOIS (b) ICANN (c) IAN (d) FORTRAN Answer: (d) FORTRAN 14. (a) 128bit (b) 16block (c) Hexadecimal (d) Binary notation Answer: (d) Binary notation 15. (a) in (b) cn (c) gov (d) pk Answer: (c) gov Very Short Answers Question 1. What is a domain? Answer: A domain is a single node of the Domain Namespace. Question 2. What is Zone? Answer: A zone is a subset of the Domain namespace generally stored in a file. Question 3. What is Domain Name Space? Answer: Domain Namespace is an entire collection of Domains, Subdomains, and Zones. Question 4. What is a Name Server? Answer: Name server manages the database of domain names and corresponding IP addresses. Question 5. What does the zone contain? Answer: A zone can contain more than one subdomain. Question 6. What does the server contain? Answer: A server can contain more than one zone file (Zones). Domain Name Meaning  DOMAIN MEANING com Commercial Organisation edu Educational Institutions gov Government (US) mil Military groups org Nonprofit Organization net Networking organization info Information service providers Part B Short Answers Question 1. Name the four parts of the URL? Answer: URL is made up of four parts-protocols, hostname, folder name, and file name. Each part has its own specific functions. Depending on the applications, additional information can be added to the URL but the common and fundamental URL consists of these four parts. Question 2. List the three components of DNS? Answer: 1. NameSpace 2. Name server 3. Zone Question 3. What is a Label? Answer: • The label is a string which can have a maximum of 63 characters. • Each node in that level should have different labels thereby assuring the individuality of the domain name. Question 4. Name the three domain names used in Tamil language? Answer: India, Singapore, Srilanka. Question 5. What is the Inverse domain? Answer: Inverse domain performs the opposite task of the normal DNS query. It converts the IP address to the domain name. Question 6. What is Zone File? Answer: Every zone has a server which contains a database called a zone file. Question 7. What are the two copies of the zone file? Answer: There are two copies of zone files available, they are 1. Masterfile 2. Slave file. Question 7. Write the demerits of the Flat namespace? Answer: The major disadvantage of flat namespaces is that they cannot be used in large systems. Because they need to be accessed and controlled centrally to avoid ambiguity and redundancy. Part C Explain In Brief Answer Question 1. What are the fundamentals of URL? Answer: • URL is made up of four parts-protocols, hostname, folder name, and file name. • Each part has its own specific functions. Depending on the applications, additional information can be added to the URL but the common and fundamental URL consists of these four parts. • Protocol • Domain name/Hostname • Folders • Filename with extension Question 2. What is meant by Label? Answer: Label: It is a string which can have a maximum of 63 characters. Each node in that level should have different labels thereby assuring the individuality of the domain name. In other words, Labels are the names given to domains. The domain is a subtree in the domain name space tree structure. The domain can be further divided into subdomains. Question 3. Write a note on Country top-level domain names. Answer: • Country domain uses 2-character country abbreviation according to country. • For e.g., google.in – for INDIA, Google’s for US.Some of the Domain Name and their meaning listed below. table Question 4. Explain the types of Name servers? Answer: Types of Name Servers: There are three types of Name Servers which control the entire Domain Name System: Root Name Server – top-level server which contains the entire DNS tree, maintained by ICANN. There are 13 servers. Primary/Master Name Server- contains zone resource records. These records are updatable by domain name holders such as organizations. Secondary/Slave Name Server – contains a copy of primary server files. This server has no authority to update but reduces the workload of the master server by sharing the queries. Part IV Explain In Detail Question 1. Explain the Basic rules of Domain names? Answer: Basic rules of Domain names: 1. A domain can consist of Alphabets a through z, and the digits 0 through 9. 2. Hyphens are allowed, but hyphens can not be used as the first character of a domain name. 3. Spaces are not allowed. 4. Special symbols (such as !$, &, _ and so on) are not permitted, length of 2, and the maximum length of 63 characters.
5. The entire name may be at most 253 characters long.
6. Domain names are not case-sensitive.(It may be upper, lower, or mixing of both case letters)

Question 2.
Write a note on the Hierarchical namespace?
Answer:

• To avoid the major disadvantage of the Flat namespace, the hierarchical namespace is used in large.
• A hierarchical namespace is where the name is made up of several parts.
• The first part may represent the nature of the organization,
• The second part may represent the name of the organization, and
• Third-party may represent the department of the organization and so on.
• In this way, the power to control the namespace can be decentralized.
• The centralized authority can be given to nature and then the name of the organization and so on.
• To achieve a hierarchical namespace, Domain Name Space was designed.