IP Address Location Lookup
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Last Updated 12/8/2013
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The Internet Protocol (IP) is a data-oriented protocol used for communicating data across a packet-switched internetwork. IP is a network layer protocol in the internet protocol suite and is encapsulated in a data link layer protocol (e.g., Ethernet). As a lower layer protocol, IP provides the service of communicable unique global addressing amongst computers. This implies that the data link layer need not provide this service. Ethernet provides globally unique addresses except it is not globally communicable (i.e., two arbitrarily chosen Ethernet devices will only be able to communicate if they are on the same bus). The difference is that IP is concerned with the final destination of data packets. Ethernet is concerned with only the next device (computer, router, etc.) in the chain. The final destination and next device could be one and the same (if they are on the same bus) but the final destination could be on the other side of the world.
Data from an upper layer protocol is encapsulated inside one or more packets/datagrams (the terms are basically synonymous in IP). No circuit setup is needed before a host tries to send packets to a host it has previously not communicated with (this is the point of a packet-switched network), thus IP is a connectionless protocol. This is quite unlike Public Switched Telephone Networks that require the setup of a circuit before a phone call may go through (a connection-oriented protocol).
Services provided by IP
Because of the abstraction provided by encapsulation, IP can be used over a heterogenous network (i.e., a network connecting two computers can be any mix of Ethernet, ATM, FDDI, Wi-fi, Token ring, etc.) and it makes no difference to the upper layer protocols. All the data link layers can (and do) have their own set of addressing (or possibly the complete lack of it) and the need to resolve IP addresses to data link addresses is needed. This resolving is addressed by the Address Resolution Protocol (ARP).
IP provides an unreliable service (i.e., best effort delivery). This means that the network makes no guarantees about the packet and none, some, or all of the following may apply:
- data corruption
- out of order (packet A may be sent before packet B, but B can arrive before A)
- duplicate arrival
- lost or dropped/discarded
In terms of reliability the only thing IP does is ensure the IP packet's header is error-free through the use of a checksum. This has the side-effect of discarding packets with bad headers on the spot, and with no required notification to either end (though an ICMP message may be sent).
To address any of these reliability issues, an upper layer protocol must handle it. For example, to ensure in-order delivery the upper layer may have to cache data until it can be passed up in order.
The primary reason for the lack of reliability is to reduce the complexity of routers. While this does give routers carte blanche to do as they please with packets, anything less than best effort yields a poorer experience for the user. So, even though no guarantees are made, the better the effort made by the network, the better the experience for the user.
IP addressing and routing
Perhaps the most complex aspects of IP are IP addressing and routing. Addressing refers to how end hosts become assigned IP addresses and how subnetworks of IP host addresses are divided and grouped together. IP routing is performed by all hosts, but most importantly by internetwork routers, which typically use either interior gateway protocols (IGPs) or external gateway protocols (EGPs) to help make IP datagram forwarding decisions across IP connected networks.
An IP address (Internet Protocol address) is a unique number that devices use in order to identify and communicate with each other on a computer network utilizing the Internet Protocol standard (IP). Any participating network device — including routers, computers, time-servers, printers, Internet fax machines, and some telephones — must have its own unique address. An IP address can also be thought of as the equivalent of a street address or a phone number (compare: VoIP) for a computer or other network device on the internet. Just as each street address and phone number uniquely identifies a building or telephone, an IP address can uniquely identify a specific computer or other network device on a network.
An IP address can appear to be shared by multiple client devices either because they are part of a shared hosting web server environment or because a proxy server (e.g. an ISP or anonymizer service) acts as an intermediary agent on behalf of its customers, in which case the real originating IP addresses might be hidden from the server receiving a request. The analogy to telephone systems would be the use of predial numbers (proxy) and extensions (shared). IP addresses are managed by the Internet Assigned Numbers Authority. IANA generally assigns super-blocks to Regional Internet Registries, who in turn allocate smaller blocks to Internet Service Providers and enterprises.
IP address How To Contents
- 1 Dynamic and static IP addresses
- 2 IP versions
Dynamic and static IP addresses
IP addresses may either be assigned permanently (for example, to a server which is always found at the same address) or temporarily from a pool of available addresses.
Dynamic IP Address
Dynamic IP addresses are issued to identify non-permanent devices such as personal computers or clients. Internet Service Providers (ISPs) use dynamic allocation to assign addresses from a small pool to a larger number of customers. This is used for dial-up access, WiFi and other temporary connections, allowing a portable computer user to automatically connect to a variety of services without needing to know the addressing details of each network. Users with a dynamic IP may have trouble running their own email server. In recent years services such as mail-abuse.org have collected lists of these address ranges and can be used as a block list. The most common protocol used to dynamically assign addresses is Dynamic Host Configuration Protocol (DHCP). DHCP includes a lease time which determines how long the requester can use an address before requesting its renewal, allowing addresses to be reclaimed if the requester goes offline. The DHCP server listens for requests and then assigns an address. System administrators may set the DHCP server so that it assigns addresses at random, or based on a predetermined policy. Once a machine receives its new IP address, it may tell that address to a Dynamic DNS server. It is common to use dynamic allocation for private networks. Since private networks rarely have an address shortage, it is possible to assign the same address to the same computer on each request or to define an extended lease time. These two methods simulate static IP address assignment.
Static IP Address
Static IP addresses are used to identify semi-permanent devices with constant IP addresses. Servers typically use static IP addresses. The static address can be configured directly on the device or as part of a central DHCP configuration which associates the device's MAC address with a static address.
The Internet Protocol has two primary versions in use. Each version has its own definition of an IP address. Because of its prevalence, "IP address" typically refers to those defined by IPv4.
IP version 4
IPv4 uses 32-bit (4 byte) addresses, which limits the address space to 4,294,967,296 (232) possible unique addresses. However, many 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, and as the number of addresses available is consumed, an IPv4 address shortage appears to be inevitable in the long run. This limitation has helped stimulate the push towards IPv6, which is currently in the early stages of deployment and is currently the only contender to replace IPv4.
IP version 5
What would be considered IPv5 existed only as an experimental non-IP real time streaming protocol called ST2, described in RFC 1819. In keeping with standard UNIX release conventions, all odd-numbered versions are considered experimental, and this version was never intended to be implemented, thus not abandoned. RSVP has replaced it to some degree.
IP version 6
In IPv6, the new (but not yet widely deployed) standard protocol for the Internet, addresses are 128 bits wide, which, even with a generous assignment of netblocks, should suffice for the foreseeable future. In theory, there would be exactly 2128, or about 3.403 × 1038 unique host interface addresses. This large address space will be sparsely populated, which makes it possible to again encode more routing information into the addresses themselves.
This magnitude of IPs available will be necessary in the future as mobile phones, cars and all types of personal devices come to rely on the internet for everyday purposes.