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BZUPAGES.COM Presented to: Sir. Muizuddin sb Presented by: M.Sheraz Anjum Atif Aneaq Khurram Shehzad Wasif Laeq Taha Khan Bukhtyar Ali Hafiz Shahrukh Muhammad Arqum Roll NO.07-16 Roll NO. 07-15 Roll NO. 07-32 Roll NO. 07-01 Roll NO. 07-06 Roll NO. 07-18 Roll NO. 07-22 Roll NO. 06-24 Bs(IT) 6th Department Of Information Technology (Institute of Computing) B-Z-U 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. 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. 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. 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. 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. 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. BZUPAGES.COM Domain name space (Cont.) BZUPAGES.COM Domain name space (Cont.) • Administrative responsibility over any zone may be divided, thereby creating additional zones. 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 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 • Label ifhosting is sub domain of .com and www is the sub domain of ifhosting.com 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/ 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 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. 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 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. 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. BZUPAGES.COM Name servers (Cont.) BZUPAGES.COM Primary and Secondary NS • Primary name server and secondary name servers are required. 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. 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. BZUPAGES.COM Operation • • • • Address resolution mechanism Record caching Client lookup Other applications BZUPAGES.COM Address Resolution Mechanism 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 BZUPAGES.COM Client lookup • Users generally do not communicate directly with a DNS resolver. 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) 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. 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. 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 BZUPAGES.COM Domain Tools www.whois.domaintools.com/ Store all NS and registration information about each WWW. BZUPAGES.COM BZUPAGES.COM BZUPAGES.COM