Internet protocols.md (1390B)
1 +++ 2 title = 'Internet protocols' 3 +++ 4 # Internet protocols 5 Protocols — rules to communicate over network 6 7 - TCPI/IP on ARPANET in 1982 8 - works locally (LAN) & on network 9 - various models of communication, mainly client/server, but also peer-to-peer and others. 10 11 IP (internet protocol): 12 13 - address in IPv4 is 32 bits 14 - associated with max 1 device at a time 15 - written as 4 dot-separated bytes 16 - transfers data packets from source to destination (like postal service) 17 - packets created by IP software contain: 18 - header with source/destination address, length, etc. 19 - data 20 21 TCP (transmission control protocol) 22 23 - provides guarantee that packet is delivered 24 - provides 2-way communication 25 - analogy: telephone status report 26 - adds ports (numbers) representing destination process on destination computer (with some being standard) 27 - higher-level protocols like SMTP, FTP, HTTP are built on top of this 28 29 UDP (user datagram protocol): 30 31 - like TCP 32 - builds IP 33 - provides ports 34 - unlike TCP 35 - no connection concept 36 - no transmission guarantee 37 - UDP is lightweight, better for one-time messages 38 39 DNS (domain name service) 40 41 - "phone book" 42 - maps IP to hostnames (www.example.org) 43 - top-level domain is the last part (.com, .org, . edu, etc.) 44 45 Analogy: IP is a telephone network, TCP is a conversation, UDP is a voicemail message, DNS is the yellow pages/directory assistance