What is an IP?
The Internet Protocol (IP) is the main communication protocol used in the Internet Protocol Suite to relay datagrams across network boundaries. Its routing function can realize the Internet and fundamentally establish the Internet.
The task of IP is to transmit data packets from the source host to the destination host only based on the IP address in the packet header. To this end, IP defines a data packet structure that encapsulates the data to be transmitted. It also defines the addressing method used to mark datagrams with source and destination information.
Historically, IP is a connectionless datagram service in the original transmission control program introduced by Vint Cerf and Bob Kahn in 1974. It was supplemented by connection-oriented services and became the basis of the Transmission Control Protocol (TCP). Therefore, the Internet Protocol Suite is commonly referred to as TCP/IP.
What is a hostname
In computer networks, a host name (usually nodename) is a label assigned to a device connected to a computer network and used to identify the device in various forms of electronic communication (for example, the World Wide Web). The host name can be a simple name consisting of a single word or phrase, or it can be a structured name. Each hostname usually has at least one numeric network address associated with it, which is used to route packets for performance and other reasons.
The Internet host name may be appended with the name of the Domain Name System (DNS) domain, which is separated from the host-specific label with a period ("dot"). In the latter form, the host name is also called the domain name. If the domain name is fully specified, including the top-level domain of the Internet, the host name is called a fully qualified domain name (FQDN). Host names including DNS domains are usually stored in the domain name system together with the IP address of the host they represent, with the purpose of mapping the host name to an address, or reverse processing.