1. BZUPAGES.COM

2. Presented to: Sir. Muizuddin sb Presented by: M.Sheraz Anjum Roll NO.07-16 Atif Aneaq Roll NO. 07-15 Khurram Shehzad Roll NO. 07-32 Wasif Laeq Roll NO. 07-01 Taha Khan Roll NO. 07-06 Bukhtyar Ali Roll NO. 07-18 Hafiz Shahrukh Roll NO. 07-22 Muhammad Arqum Roll NO. 06-24 Bs(IT) 6 th Department Of Information Technology (Institute of Computing) B-Z-U B.Z.U

3. BZUPAGES.COM Domain Name A domain name is an identification label that defines a scope of administrative autonomy, authority, or control in the Internet, based on the Domain Name System (DNS). Simply it is a user friendly name.

4. BZUPAGES.COM Domain Name System Definition: It is a hierarchical naming system for computers, services, or any resource connected to the Internet or a private network. Associates various information with domain names assigned to each of the participants.

5. BZUPAGES.COM Explanation It translates domain names meaningful to humans into the numerical identifiers associated with networking equipment for the purpose of locating and addressing these devices worldwide. It serves as the "phone book" for the Internet by translating human-friendly computer hostnames into IP addresses. For example: www.bzupages.com translates to 69.162.70.115.

6. BZUPAGES.COM Characteristics Domain names are assigned to groups of Internet users. It is independent of each user's physical location. Is easier to remember than IP addresses such as 208.77.188.166.

7. BZUPAGES.COM An Intro To basic Authorities The Domain Name System distributes the responsibility of assigning domain names and mapping those names to IP addresses by designating authoritative name servers for each domain. Authoritative name servers are assigned to be responsible for their particular domains, and in turn can assign other authoritative name servers for their sub-domains.

8. BZUPAGES.COM Domain name space Consists of a tree of domain names. Zone(Domain) consists of a collection of connected nodes, served by an authoritative name server. Single name server can host several zones.

9. BZUPAGES.COM Domain name space (Cont.)

10. BZUPAGES.COM Domain name space (Cont.) Administrative responsibility over any zone may be divided, thereby creating additional zones.

11. BZUPAGES.COM Domain name formulation A domain name consists of one or more parts called labels. Labels are conventionally concatenated, by dots, such as IFhosting.com. The right-most label conveys the top-level domain

12. BZUPAGES.COM Domain name formulation (Cont) Descends from right to left. Each label to the left specifies a subdivision, or sub domain of the domain to the right. E.g in www.ifhsoting.com ifhosting wwwLabel ifhosting is sub domain of.com and www is the sub domain of ifhosting.com

13. BZUPAGES.COM Domain name formulation (Cont) This tree of subdivisions may consist of 127 levels. Each label may contain up to 63 characters The full domain name may not exceed a total length of 253 characters. thelongestlistofthelongeststuffatthelongest domainnameatlonglast.com/

14. BZUPAGES.COM Domain name formulation (Cont) The characters allowed in a label are a subset of the ASCII character set, and includes –a through z –A through Z –digits 0 through 9 –Hyphen

15. BZUPAGES.COM Domain name formulation (Cont) Hostname: It is a domain name that has at least one IP address associated. For example: The domain names www.example.com and sheikho.com are hostnames. Whereas.com is not a hostname.

16. BZUPAGES.COM Types of Domains Generic Top Level Domain (GTLD) –E.g.com.org.net Country Code Top Level Domain (CCTLD) –E.g.pk.in.un

17. BZUPAGES.COM Internationalized domain names Permitted character set of the DNS prevented the representation of names and words of many languages in their native alphabets. ICANN has approved the Punycode-based internationalized domain name (IDNA) system. – e.g محمد.com In 2009 ICANN approved the installation of IDN country code top-level domains.

18. BZUPAGES.COM Name servers The Domain Name System is maintained by a distributed database system. The nodes of this database are the name servers. Each domain has at least one authoritative DNS server. The top of the hierarchy is served by the root name servers.

19. BZUPAGES.COM Name servers (Cont.)

20. BZUPAGES.COM Primary and Secondary NS Primary name server and secondary name servers are required.

21. BZUPAGES.COM Recursive and caching name server Every DNS query must start with recursive queries at the root zone of the Domain Name System. The Domain Name System supports DNS cache servers which store DNS query results for a period of time. Many home networking routers implement DNS caches and improve efficiency in the local network.

22. BZUPAGES.COM DNS resolvers The client-side of the DNS is called a DNS resolver. Initiates and sequences queries. A DNS query may be either a non-recursive query or a recursive query.

23. BZUPAGES.COM Address resolution mechanism Record caching Client lookup Other applications Operation

24. BZUPAGES.COM Address Resolution Mechanism

25. BZUPAGES.COM Record Caching A mechanism to reduce the load on individual DNS servers. Records are cached for a period of time after an answer. Time to live (TTL) time for which a resolver caches a DNS response. Changes to DNS records do not propagate throughout the network immediately

26. BZUPAGES.COM Client lookup Users generally do not communicate directly with a DNS resolver.

27. BZUPAGES.COM Other applications Hostnames and IP addresses do not necessarily match on a one-to-one basis. There are many uses of DNS besides translating names to IP addresses. E-mail Blacklists Software Updates ( e.g an AntiVirus)

28. BZUPAGES.COM Other applications (Cont.) Multiple DNS servers are usually provided for coverage of all domains. Thirteen very powerful root servers exist to provide flexibility in case of computer failure. Dynamic DNS (also referred to as DDNS) provides clients the ability to update their IP address in the DNS. –As in case of DHCP, dynamically IP addresses are assigned to users from pool of IP addresses.

29. BZUPAGES.COM Domain name registration The right to use a domain name is given by domain name registrars. – e.g dotcomgenie.com It is credited by the Internet Corporation for Assigned Names and Numbers (ICANN). A registry is responsible for maintaining the database of names registered within the Top Level Domain (TLD) it administers. The registry receives registration information from each domain name registrar authorized to assign names in the corresponding TLD.

30. BZUPAGES.COM Domain name registration (Cont) The registry publishes this information using a special service, the WHOIS protocol. Some domain name registries, often called network information centers (NIC), also function as registrars to end-users. The registrants (users of a domain name) are customers of the registrar

31. BZUPAGES.COM Domain Tools www.whois.domaintools.com/ Store all NS and registration information about each WWW.

32. BZUPAGES.COM