load distribution

　The load dispersion is the technology and operation that prepares multiple systems with the same function, and separates the processing so that the amount of work to be handled becomes uniform.In the case of a network, it refers to placing multiple servers in parallel in parallel so that access is not concentrated on specific devices.

　There are two types of static and dynamic sorting of access in load dispersion.In the static method, regardless of the status of the connection destination server, the sort is sorted based on the rules specified in advance.On the other hand, in the case of a dynamic method, access is sorted according to the state of the server.

到着順に振り分ける

　静的方式の代表がラウンドロビンだ。ラウンドロビンでは並行稼働する複数のサーバーに対し、順番にアクセスを振り分けていく（PICT1）。例えばA、B、Cという3台のサーバーを並行稼働させているとする。最初のアクセスはAに、2番目はB、3番目はCと振り分け、4番目は再びAに割り振るという具合だ。

　In this method, the response to the terminal is significantly delayed depending on the server operating status.Since the server to be connected is only changed in order, it may be guided to the downed server.

　"DNS Round Robin" is the load dispersion of the web server based on the round robin.DNS roundrobin realizes load dispersion using the name resolution of DNS (Domain Name System).DNS usually registers an IP address corresponding to the host name one -on -one.Returns one IP address for inquiries to one host name.However, in the case of DNS roundrobin, multiple IP addresses are registered for one host name.When the client requests a name resolution, respond in multiple registered IP addresses in order.It is a mechanism to sort the server of the connection destination by guiding a different destination for each client of the connection source.

　One of the advantages of DNS roundrobin is that it is easy to implement.By simply rewriting the registration information of the DNS server published outside, access to multiple servers can be distributed.There is no need to prepare a dedicated device.

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