network service this article is about services provided by and to networked computers for information about internet connections see network service provider for a hierarchical list of network services see categorynetwork service in computer networking a network service is an application running at the network application layer and above that provides data storage manipulation presentation communication or other capability which is often implemented using a clientserver or peertopeer architecture based on application layer network protocols each service is usually provided by a server component running on one or more computers often a dedicated server computer offering multiple services and accessed via a network by client components running on other devices however the client and server components can both be run on the same machine clients and servers will often have a user interface and sometimes other hardware associated with it examples examples are the domain name system dns which translates domain names to internet protocol ip addresses and the dynamic host configuration protocol dhcp to assign networking configuration information to network hosts authentication servers identify and authenticate users provide user account profiles and may log usage statistics email printing and distributed network file system services are common services on local area networks they require users to have permissions to access the shared resources other network services include directory services email file sharing instant messaging online game printing file server voice over ip video on demand video telephony world wide web simple network management protocol time service wireless sensor network application layer application layer internet protocol suite application layer bgp dhcp dns ftp http https imap ldap mgcp mqtt nntp ntp pop oncrpc rtp rtsp rip sip smtp snmp ssh telnet tlsssl xmpp more transport layer tcp udp dccp sctp rsvp more internet layer ip ipv4 ipv6 icmp icmpv6 ecn igmp ipsec more link layer arp ndp ospf tunnels l2tp ppp mac ethernet dsl isdn fddi more vte osi modelby layer 7 application layer nntp sip ssi dns ftp gopher http nfs ntp smpp smtp snmp telnet dhcp netconf more 6 presentation layer mime xdr asn1 5 session layer named pipe netbios sap pptp rtp socks spdy 4 transport layer tcp udp sctp dccp spx 3 network layer ip ipv4 ipv6 icmp ipsec igmp ipx appletalk x25 plp 2 data link layer atm arp isis sdlc hdlc cslip slip gfp plip ieee 8022 llc mac l2tp ieee 8023 frame relay itut ghn dll ppp x25lapb q921 lapd q922 lapf 1 physical layer eiatia232 eiatia449 itut vseries i430 i431 pdh sonetsdh pon otn dsl ieee 8023 ieee 80211 ieee 80215 ieee 80216 ieee 1394 itut ghn phy usb bluetooth rs232 rs449 vte in computer network programming the application layer is an abstraction layer reserved for communications protocols and methods designed for processtoprocess communications across an internet protocol ip computer network application layer protocols use the underlying transport layer protocols to establish hosttohost connections for network services tcpip network services port numbers list of tcp and udp port numbers many internet protocolbased services are associated with a particular wellknown port number which is standardized by the internet technical governance for example worldwideweb servers operate on port 80 and email relay servers usually listen on port 25 tcp versus udp different services use different packet transmission techniques in general packets that must get through in the correct order without loss use tcp whereas real time services where later packets are more important than older packets use udp for example file transfer requires complete accuracy and so is normally done using tcp and audio conferencing is frequently done via udp where momentary glitches may not be noticed udp lacks builtin network congestion avoidance and the protocols that use it must be extremely carefully designed to prevent network collapse information technology portal internet hosting service web hosting service dns hosting service email hosting service vtemajor fields of computer sciencenote this template roughly follows the 2012 acm computing classification systemhardware printed circuit board peripheral integrated circuit very large scale integration systems on chip socs energy consumption green computing electronic design automation hardware acceleration computer systemsorganization computer architecture embedded system realtime computing dependability networks network architecture network protocol network components network scheduler network performance evaluation network service software organization interpreter middleware virtual machine operating system software quality software notationsand tools programming paradigm programming language compiler domainspecific language modeling language software framework integrated development environment software configuration management software library 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