Table of contents [ hide ] Basic theory CAP States that any distributed data store can provide only two of the following three guarantees. Consistency Every read receives the most recent write or an error. Availability Every request receives a (non-error) response, without the guarantee that it contains the most recent write. Partition tolerance The system continues to operate despite an arbitrary number of messages being dropped (or delayed) by the network between nodes. Typical architecture of distributed systems When a network partition failure happens, it must be decided whether to do one of the following: CP: cancel the operation and thus decrease the availability but ensure consistency AP: proceed with the operation and thus provide availability but risk inconsistency. BASE Basically-available, soft-state, eventual consistency. Base theory is the practical application of CAP theory, that is, under the premise of the existence of partitions and copies, through certain syste
Table of contents [ hide ] The Internet Model includes 4 layers and 7 layers, usually, we use 7 layers for education and communication. Physical Specifies how data is processed into bits and physically transferred over cables. Media type. Connector type. Signal strength. Coding Mechanism. Data link Provides the link for how data packaged into frames is communicated through hardware to transport across a medium. Medium Access. Physical Address. Frame. Ethernet_frame: Network The network layer provides the functional and procedural means of transferring packets from one node to another connected in "different networks" Defines the format of the logical address. Provide routing and best path. IPV4 packet Icmp ICMP messages are typically used for diagnostic or control purposes or generated in response to errors in IP operations (as specified in RFC 1122). ICMP errors are directed to the source IP address of the originating packet. It is used by network devices, like routers