Contents
What layer of TCP IP is DNS?
TCP/IP Protocol Architecture Model
| OSI Ref. Layer No. | OSI Layer Equivalent | TCP/IP Protocol Examples |
|---|---|---|
| 5,6,7 | Application, session, presentation | NFS, NIS, DNS, LDAP, telnet , ftp , rlogin , rsh , rcp , RIP, RDISC, SNMP, and others |
| 4 | Transport | TCP, UDP, SCTP |
| 3 | Network | IPv4, IPv6, ARP, ICMP |
| 2 | Data link | PPP, IEEE 802.2 |
Does DNS rely on TCP IP?
DNS uses TCP for Zone transfer and UDP for name, and queries either regular (primary) or reverse. UDP can be used to exchange small information whereas TCP must be used to exchange information larger than 512 bytes.
What are the layers of the TCP IP stack?
4 The TCP/IP Protocol Stack is made up of four primary layers: the Application, Transport, Network, and Link layers (Diagram 1). Each layer within the TCP/IP protocol suite has a specific function. When the layers of the model are combined and transmitted, communication between systems can occur.
Does DNS use UDP or TCP?
DNS has always been designed to use both UDP and TCP port 53 from the start 1 , with UDP being the default, and fall back to using TCP when it is unable to communicate on UDP, typically when the packet size is too large to push through in a single UDP packet.
What layer is nslookup?
Tools such as ping , nslookup , etc. all work at application layer; but as you stated, the messages are sent up and down the protocol stack to work at all layers of the OSI model.
Why UDP is used in DNS?
DNS uses the User Datagram Protocol (UDP) on port 53 to serve DNS queries. UDP is preferred because it is fast and has low overhead. A DNS query is a single UDP request from the DNS client followed by a single UDP reply from the server.
Is DNS a layer 3 or 4?
DNS is a application layer protocol, because DNS query and answer is the application level communications. Application layer only understand the query and answer section in the DNS packet. so application layer DNS query/answer is encapsulated in layer 4 udp then layer 3 IP…..and so on.
Where does DNS sit in the protocol stack?
DNS is in effect an application that is invoked to help out the HTTP application, and therefore does not sit “below” HTTP in the OSI stack. DNS itself also makes use of UDP and more rarely TCP, both of which in turn use IP.
What is the difference between DNS and TCP?
DNS is an application layer protocol. All application layer protocols use one of the two transport layer protocols, UDP and TCP. TCP is reliable and UDP is not reliable.
How does Windows NT Server do host name resolution?
A Windows NT server will take the role of client when it requires access to resources that require host name resolution. The client checks to see if the name queried is its own. The client then searches a local Hosts file, a list of IP address and names stored on the local computer.
When does DNS run in parallel to http?
In OSI stack terms, DNS runs in parallel to HTTP in the Application Layer (layer 7). DNS is in effect an application that is invoked to help out the HTTP application, and therefore does not sit “below” HTTP in the OSI stack.