How to Find Your IP Address. DNS address. IPv4. IPv6
(Internet Protocol Address) is a unique address used by certain electronic devices to identify and communicate with each other on a computer network that uses the Internet Protocol (IP) standard in simpler terms, a computer address. Every participating network device including router, computer, time server, printer, internet fax machine, and several phones can have their own unique address.
IP addresses can also be considered equivalent to street addresses or telephone numbers (compare: VoIP (voice over (the) internet protocol)) for computers or other network devices on the Internet. Just as each street address and telephone number uniquely identifies a building or telephone, an IP address can uniquely identify a particular computer or other network device on the network. However, the IP address is different from other contact information, because the user’s IP address relationship with his name is not publicly available information.
IP addresses can be shared by several client devices either because they are part of a shared web server environment or because the network address translator (NAT) or proxy server acts as an intermediary agent on behalf of its customers, in this case the original IP address may be hidden from the receiving server. Request. The common practice is to have NAT hide a large number of IP addresses, in the private address space specified by RFC 1918, blocks of addresses that cannot be routed on the public Internet. Only the “outside” interface of NAT needs to have an Internet forwarding address.
Most commonly, NAT devices map outside TCP or UDP port numbers to each private address inside. Just as there may be site-specific extensions on phone numbers, port numbers are site-specific extensions to IP addresses.
IP addresses are managed and created by the Internet Assigned Numbers Authority (IANA). IANA generally allocates super blocks to Regional Internet Registries, which in turn allocate smaller blocks to Internet service providers and companies.
On the Internet, the Domain Name System (DNS) links various types of information with what is called a domain name; most importantly, it functions as a “telephone book” for the Internet: it translates computer host names that can be read by humans, e.g. en.wikipedia.org, to the IP address needed by network equipment to send information. It also stores other information such as a list of mail exchange servers that receive email for a given domain. In providing keyword-based transfer services throughout the world, the Domain Name System is an important component of contemporary Internet usage.
The most basic use of DNS is translating hostnames to IP addresses. In very simple terms like a telephone book. For example, if you want to know the internet address en.wikipedia.org, the Domain Name System can be used to tell you the address 126.96.36.199. DNS also has other important uses.
What’s more, DNS makes it possible to assign Internet goals to human organizations or the problems they represent, regardless of the hierarchy of physical routing represented by numerical IP addresses. Because of this, hyperlinks and Internet contact information can remain the same, whatever the current IP routing settings, and can take human-readable forms (such as “wikipedia.org”) that are easier to remember than IP addresses (such as 188.8.131.52). People take advantage of this when they read meaningful URLs and email addresses regardless of how the machine will find them.
The Domain Name System distributes the responsibility for assigning domain names and mapping them to IP networks by allowing authoritative servers for each domain to track their own changes, avoiding the need for a central registrar to continue to consult and
The practice of using names as more humanly readable abstractions from numerical addresses of machines on a network even existed before TCP / IP, and continued until the ARPAnet era. At that time, however, a different system was used, because DNS was only discovered in 1983, shortly after TCP / IP was used. With older systems, every computer on the network retrieved a file called HOSTS.TXT from a computer on SRI (now SRI International). The HOSTS.TXT file is mapped numeric addresses to names. The host file still exists on most modern operating systems, either by default or through configuration, and allows the user to specify an IP address (e.g. 184.108.40.206) to be used for the hostname (eg. Www.example.net) without checking DNS. In 2006, the host file functioned primarily for troubleshooting DNS errors or for mapping local addresses to more organic names. Systems based on host files have inherent limitations, because of the clear requirements that every time a specific computer address is changed, every computer that attempts to communicate with it will need an update to its host file.
Network growth is called for a more scalable system: it records changes in host addresses in one place. Other hosts will learn about changes dynamically through the notification system, thereby completing a globally accessible network of all associated hostnames and IP addresses.
At Jon Postel’s request, Paul Mockapetris discovered the Domain Name System in 1983 and wrote the first implementation. The original specifications appeared in RFC 882 and 883. In 1987, the publication of RFC 1034 and RFC 1035 updated the DNS specifications and made RFC 882 and RFC 883 obsolete. Some newer RFCs have proposed various extensions to the core DNS protocol.
In 1984, four Berkeley students, Douglas Terry, Mark Painter, David Riggle and Songnian Zhou wrote the first UNIX implementation, which was managed by Ralph Campbell afterwards. In 1985, Kevin Dunlap of DEC significantly rewritten the DNS implementation and named it BIND (Berkeley Internet Name Domain, formerly: Berkeley Internet Name Daemon). Mike Karels, Phil Almquist and Paul Vixie have maintained BIND since then. BIND was transported to the Windows NT platform in the early 1990s.
Due to BIND’s long history of security problems and exploits, several alternative nameserver / resolver programs have been written and distributed in recent years.
How DNS works in theory:
A domain name space consists of a domain name tree. Each node or branch in the tree has one or more resource records, which store information related to the domain name. The tree is divided into zones. A zone consists of a collection of connected nodes that are served by an authoritative DNS name server. (Note that a single name server can host multiple zones.)
When a system administrator wants to let another administrator control part of the domain namespace in his authority zone, he can delegate control to another administrator. This divides parts of the old zone into new zones, which are under the authority of the second administrator’s name server. The old zone becomes no longer authoritative for what is under the authority of the new zone.
The resolver looks for information related to the node. Resolver knows how to communicate with name servers by sending DNS requests, and handling DNS responses. Completion usually requires repetition through several name servers to find the information needed.
Some resolvers function simply and can only communicate with a single name server. This simple resolver relies on recurring name servers to do the job of finding information for them.
Internet Protocol version 4 is the fourth iteration of the Internet Protocol (IP) and it is the first version of the protocol to be used widely. IPv4 is the dominant network layer protocol on the Internet and besides IPv6 it is the only protocol used on the Internet.
This is explained in IETF RFC 791 (September 1981) which made RFC 760 obsolete (January 1980). The United States Department of Defense also standardized it as MIL-STD-1777.
IPv4 is a data-oriented protocol that will be used on internetwork-enabled packages (e.g., Ethernet). This is the best effort protocol because it does not guarantee delivery. It does not make a guarantee on the truth of the data; This can result in duplicate packages and / or packages that do not match the order. These aspects are handled by upper-layer protocols (e.g., TCP, and in part by UDP).
The whole purpose of IP is to provide a unique global computer addressing to ensure that two computers communicating through the Internet can uniquely identify each other.
IPv4 uses a 32-bit (4-byte) address, which limits the address space to 4,294,967,296 possible unique addresses. However, some are reserved for special purposes such as private networks (~ 18 million addresses) or multicast addresses (~ 1 million addresses). This reduces the number of addresses that can be allocated as public Internet addresses. Because of the number of available addresses consumed, lack of IPv4 addresses seems unavoidable, but Network Address Translation (NAT) has significantly delayed this inevitability.
This limitation has helped to stimulate a push towards IPv6, which is currently in the early stages of deployment and is currently the only competitor to replace IPv4.
Initially, the IP address is divided into two parts:
* Network ID: first octet
* Host id: last three octets
This creates an upper limit of 256 networks. When the network begins to be allocated, this immediately looks inadequate.
To overcome this limit, various network classes are defined, in a system that becomes known as a classful network. Five classes were created (A, B, C, D, & E), three of which (A, B, & C) have different lengths for network fields. The remaining address fields in these three classes are used to identify hosts on the network, which means that each network class has a different maximum number of hosts. Thus there are a number of networks with many host addresses and many networks with only a few addresses. Class D for multicast addresses and class E is reserved.
Around 1993, these classes were replaced with Classless Inter-Domain Routing (CIDR) schemes, and the previous scheme was dubbed “classful”. The main advantage of CIDR is that it allows the re-division of Class A, B & C networks so that smaller (or larger) address blocks can be allocated to entities (such as Internet service providers, or their customers) or Local Area Networks.
Assignments of actual addresses are not arbitrary. The basic principle of routing is that the address encodes information about the location of the device on the network. This implies that the address assigned to one part of the network will not function on another part of the network. The hierarchical structure, created by CIDR and overseen by the Internet Assigned Numbers Authority (IANA) and Regional Internet Registries (RIR), manages Internet address assignments throughout the world. Each RIR maintains a publicly searchable WHOIS database that provides information about assigning IP addresses; information from this database plays a central role in various tools that attempt to find geographical IP addresses.
Internet Protocol version 6 (IPv6) is a network layer protocol for switch-packet internetworks. It was designated as the successor to IPv4, the current version of Internet Protocol, for general use on the Internet.
The main improvement brought about by IPv6 is a much larger address space which allows greater flexibility in assigning addresses. While IPv6 can support 2128 (around 3.4 ‘1038) addresses, or around 5’ 1028 addresses for about 6.5 billion people each  alive today. However, it is not the intention of the designers of IPv6, to provide a unique unique address for each individual and each computer. Conversely, extended address length eliminates the need to use network address translation to avoid address fatigue, and also simplifies aspects of address assignment and new numbers when changing providers.
In the early 1990s, it was clear that changes to the classless network introduced a decade earlier were not enough to prevent fatigue of IPv4 addresses and further changes to IPv4 were needed.  In the winter of 1992, several proposed systems were circulated and in the fall of 1993, the IETF announced the call for white documents (RFC 1550) and the creation of “IP, Next Generation” (Area IPng) working groups.  
IPng was adopted by the Internet Engineering Task Force on July 25, 1994 with the establishment of several “Next Generation” (IPng) working groups.  In 1996, a series of RFCs were released defining IPv6, starting with RFC 2460. (Incidentally, IPv5 is not a successor to IPv4, but an experimental stream-oriented streaming protocol intended to support video and audio.)
It is hoped that IPv4 will be supported with IPv6 in the future. IPv4 specific nodes (clients or servers) will not be able to communicate directly with IPv6 nodes, and must go through intermediaries
For the most part, IPv6 is a conservative extension of IPv4. Most transport and application layer protocols require little or no change to work on IPv6; exceptions are application protocols that embed network layer addresses (such as FTP or NTPv3).
Applications, however, usually need minor changes and recompilation to run IPv6.
Larger address space:
The main feature of IPv6 that drives adoption today is the larger address space: addresses in IPv6 are 128 bits long compared to 32 bits in IPv4.
Larger address space avoids the potential of running out of IPv4 address space without the need to translate network addresses (NAT) and other devices that break down the nature of end-to-end Internet traffic. NAT may still be needed in rare cases, but Internet engineers admit that it will be difficult on IPv6 and try to avoid it wherever possible. This also makes administration of medium and large networks simpler, by avoiding the need for complex subnetting schemes. Subnetting will, ideally, return to its purpose of logical segmentation of IP networks for optimal routing and access.
The disadvantage of large address sizes is that IPv6 carries some bandwidth that exceeds IPv4, which can be detrimental to areas where bandwidth is limited (header compression can sometimes be used to overcome this problem). IPv6 addresses are harder to remember than IPv4 addresses, although IPv4 addresses are more difficult to memorize than Domain Name System (DNS) names. The DNS protocol has been modified to support IPv6 and also IPv4.
Automatic host configuration without citizenship:
IPv6 hosts can be configured automatically when connected to a routed IPv6 network. When first connected to the network, a host sends a local-link multicast request for its configuration parameters; if configured correctly, the router responds to such requests with router ad packages containing network layer configuration parameters.
If IPv6 automatic configuration does not match, a host can use stateful automatic configuration (DHCPv6) or manually configured. Stateless automatic configuration is only suitable for hosts: the router must be configured manually or by other means
IPv6 defines 3 unicast address scopes: global, site and link.
Site-local addresses are valid non-local-link addresses within the scope of the site that are administratively determined and cannot be exported outside of them.
The accompanying IPv6 specification further determines that only link-local addresses can be used when creating ICMP Forwarding Messages [ND] and as the next stepping address in most routing protocols.
This limitation does indeed imply that IPv6 routers must have next-hop link-local addresses for all routes that are directly connected (routes that routers are given and next-hop routers share common subnet prefixes).