Protocol
HTTP protocol: Hypertext Transfer Protocol.
DNS: domain name resolution.
(1) Recursive query
Recursive query is a query mode of the DNS server. In this mode, the DNS server must use an accurate query result to reply to the client after receiving the client request. If the DNS server does not store the query DNS information locally, Then the server will query other servers and submit the returned query results to the client. The query between the client and the server is a recursive query. The recursive query tells the client IP.
(2) Iterative query of the
DNS server. Another query method is iterative query. The DNS server will provide the client with other DNS server addresses that can resolve the query request. When the client sends a request, the DNS server does not directly reply to the query result. It tells the client the address of another DNS server, the client is submitting a request to this DNS server, and iterates until the result of the query is returned. The query between servers is iterative query.
TCP protocol: Transmission Control Protocol (TCP) is a
connection -oriented , reliable, byte stream-based transport layer communication protocol.
TCP is designed to adapt to the layered protocol hierarchy that supports multiple network applications.
The paired processes in host computers connected to different but interconnected computer communication networks rely on TCP to provide reliable
communication services. TCP assumes that it can obtain simple and possibly
unreliable datagram services from lower-level protocols . In principle, TCP should be able to operate on
various communication systems ranging from hard-wired connections to packet-switched or circuit-switched networks.
UDP protocol: The Internet protocol suite supports a connectionless transmission protocol, which is called
User Datagram Protocol (UDP). UDP provides
a way for applications to send encapsulated IP packets without establishing a connection.
The transport layer of the Internet has two main protocols that complement each other. The connectionless thing is UDP,
which
does nothing special except for sending data packets to applications and allowing them to construct their own protocols at the required level . The connection-oriented one
is TCP, which does almost everything.
ARP protocol: Convert IP address to MAC address (address resolution)
-a can view the ARP cache table
-d clear the ARP cache table, statically bound ARP entries will always exist, even if the system restarts
, but -d can be cleared; The ARP entry is dynamically learned, and the aging time is 120s.
If no address of the MAC host is received within the specified aging time, it will be deleted
.
-s Binding ARP entry
RARP protocol: convert MAC address to IP address (reverse address resolution)
ICMP network layer protocol (control message protocol): error frame detection and feedback mechanism, ping command/route
tracking command uses ICMP
protocol.
Ping command parameters: -t: always execute the command
-a: display the host name of the other party
-l+bytes: change the ping packet size. Generally, the ping packet size is 32 bytes-
n+number: change the number of ping packets. In general, the number of ping packets is 4
NAT: is a network address translation protocol (private network to public network, public network to private network)
There are four network mode: host (main unit only) none NAT (static) bridge (bridge
access mode)
RIP: dynamic link routing protocol (only 15 routers can be hopped)
OSPF: routing protocol (router hops by area, each area has multiple routers)
STMP: mail transfer protocol