Difference Between Load Balancing and Round-robin DNS

Load Balancing vs Round-robin DNS | Load Balancer vs Round Robin DNS

Load Balancing and Round-robin DNS are used to distribute loads to different hosts or networks to achieve load distribution, high availability, and geographical distribution for fast delivery. Mostly, it is being used in web based internet applications for the above mentioned reasons. These days, new methodology called CDN (Content Delivery Network) is introduced, but it is mainly targeting the static content delivery only. CDN will not give instant updates, unless its host sync frequency is increased.

Load Balancing (Load Balancer)

负载平衡器是软件应用程序或网络体系结构中放置的硬件设备，以面对用户端，显然是在防火墙后面。基本上，将分配带有用于用户与服务端口号的用户交互的IP地址的负载平衡器。例如，当您获得Web Load Balancer时，您将从提供商那里获得一个IP地址，仅使用DNS记录映射。如果要将其用于Web服务器，则需要在Load Balancer中创建端口80。在负载平衡器的后面，您可以拥有Sever Farm的相同服务，并具有相同的内容和配置。通过您定义的负载平衡器后面的主机，来负载平衡器IP的HTTP请求中有一定比例将分发给主机。您需要确保的一件事是，所有主机服务器都与相同的内容和配置同步，然后只有用户才能获得相同的内容。

这种体系结构将帮助我们通过冗余主机提高高可用性。负载平衡器有两种类型。一个是本地或数据中心负载平衡器，另一个是全球负载平衡器。阅读全球负载平衡器与本地或数据中心负载平衡器之间的差异。

Round-robin DNS

DNS is the Domain Name Systems distributed in multiple databases to provide human readable and usable identification for hosts. Hosts are identified by their IP, and a name is assigned to that IP in the DNS server to avoid remembering the IP address to reach that host. For example, when you request for differencebetween.com your local DNS server will provide the host details to communicate. Generally, it’s a single IP address of the differencebetween.com host. In Round-robin DNS, you can configure multiple IP addresses against a single domain name, and those IP addresses will be issued to user requests in a round robin manner. Here, the host computer or server can be anywhere in the world, which is equivalent to Global Load balancer.

DNS responds for queries, which could be defined depending on the applications. Generally it is in round robin manner; that is, if IP 1 is given to the first query, then the second query will receive IP 2, and so on. But, you can define this depending on your needs and application capabilities. If your DNS is intelligent enough to identify the geographical locations by respond time or any other mechanism, you can provide the closest IP to clients in that area.

负载均衡器和圆形机蛋白DNS有什么区别？ (1)我们可以实现numbe IP地址和端口r hiding in load balancer, but we can’t do that in DNS method. (2) DNS method, sometimes, will not work because some service providers use DNS caching, which stops getting the new IP for the client’s requests and directs to same IP, but in load balancers this will not be a problem. (3) DOS, DDOS attacks will not directly affect the host servers, instead it will affect load balancer IP, whereas in DNS method it will directly hit the host server. (4) In load balancer method , load balancer uses single TCP connection for multiple HTTP request, which will reduce the network congestion and server over head to keep track of TCP sessions, whereas in DNS method this is not applicable. （5）在HTTPS中，SSL加密和解密消耗更多的CPU使用情况，并且可以通过负载平衡器来减轻此负载，并让主机服务器执行其指定的任务；在DNS方法中也无法实现这一点。 (6) Some load balancers can have caching facility, and provide the clients with cached content without troubling host servers. This will increase the fast delivery via fast response time. (7) In Load balancers, load balancer polls host server’s health conditions, and if server is dead, it will remove the serving poll and distribute the load among others, which is also not available in DNS method. （8）负载平衡器是单个故障点，而在DNS方法中，通常，DNS记录将以层次的方式在单词上进行更新，并在本地DNS中缓存，这将有助于更快地解决IP。