Which osi layer is dns

OSI layer model in network technology

In computer and network technology, layer models have become established to break down complex processes into individual steps. Each step or each task is represented as a layer in a layer model on top of one another.

The OSI layer model is a reference model for manufacturer-independent communication systems or a design basis for communication protocols and computer networks.

The OSI layer model is very often used as a reference when it comes to depicting communication or message transmission processes. But actually the DoD layer model with the TCP / IP protocol family is much closer to reality.

OSIclassificationDoDLogsunitstreatmentComponents
applicationapplication
based
applicationDNS
HTTP
SMTP
IMAP
DataEncapsulationGateway
server
Proxy
presentationCodec
File format
communicationEncryption
transporttransmission
related and transport
oriented
transportTCP UDPSegment (TCP)
Datagram (UDP)
 
MediationInternetIPv4 IPv6Datagram Router
L3 switch
FuseNetwork accessEthernet
WIRELESS INTERNET ACCESS
frame
Frame
bit
symbol
 Switch
bridge
Bit transfer Hub
Repeater

Layer model: data transmission and addressing

To understand how protocols work in layer models, it is helpful to distinguish between addressing and data transmission.

Description of the data transfer

In the application layers 5, 6 and 7 all protocols are defined which programs and applications access directly. In the Windows network world, the SMB with NetBIOS establishes the connection to the transmission layer. If a Unix operating system comes into contact with Windows, the Samba service, for example, is used to provide applications with the resources in the Windows network on the Unix operating system.
The connection between the application and transmission layer is established via TCP ports. Applications and services receive their data via these ports.
The data stream is packed into packets by the connection-oriented transport protocol TCP or the connectionless transport protocol UDP. The Internet Protocol (IP) handles the addressing of the packets.
The bit stream is forwarded to the NDIS, which speaks to the device driver of the network card. Only the driver sends the data to the network card (NIC). From there, the data goes on the journey in the network and all details of the physical connection via different networks are handled.
With incoming data they go back the opposite way.

Description of the connection establishment

Within the application layer, the URL (Universal Resource Locator), in Windows networks the NetBIOS name of the computer, is used to identify a computer and the services that run on it.
The hosts file, in which all URLs and IP addresses are listed, is used to resolve the URL for the IP address. Since there are many URLs, the DNS (Domain Name System) was introduced, which is structured hierarchically. The so-called DNS servers are able to request unknown DNS names from the higher-level DNS server. In the Windows network, the file lmhosts or the WINS (server) is used to resolve NetBIOS names into IP addresses.
If the IP address of the transmission layer is resolved, then ARP (Address Resolution Protocol) is used to resolve the IP address into the MAC address (Media Access Control) of the network card (physical layer).
The MAC address is the only definitive address that can be used to reliably identify a computer on the network. The MAC address is permanently set on a network card.

Overview: layer models

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