aws

 

SSD volumes must be between 1 GiB - 16 TiB.

 

At this time, you cannot have a multi-AZ copy of your read replica.

 

Placement Groups are limited to a single AZ.

 

With short-polling, multiple polls of the queue may be necessary to process all messages in the queue. Additionally, SQS does NOT offer FIFO processing of messages from the queue.

 

轮询：

 

这是最早的一种实现实时 Web 应用的方案。客户端以一定的时间间隔向服务端发出请求，以频繁请求的方式来保持客户端和服务器端的同步。这种同步方案的最大问题是，当客户端以固定频率向服务器发起请求的时候，服务器端的数据可能并没有更新，这样会带来很多无谓的网络传输，所以这是一种非常低效的实时方案。

 

轮询(Polling)是指不管服务器端有没有更新，客户端(通常是指浏览器)都定时的发送请求进行查询，轮询的结果可能是服务器端有新的更新过来，也可能什么也没有，只是返回个空的信息。不管结果如何，客户端处理完后到下一个定时时间点将继续下一轮的轮询。                                    

推送或叫长连接(Long-Polling)的服务其客户端是不做轮询的，客户端在发起一次请求后立即挂起，一直到服务器端有更新的时候，服务器才会主动推送信息到客户端。 在服务器端有更新并推送信息过来之前这个周期内，客户端不会有新的多余的请求发生，服务器端对此客户端也啥都不用干，只保留最基本的连接信息，一旦服务器有更新将推送给客户端，客户端将相应的做出处理，处理完后再重新发起下一轮请求。分为长轮询和流2种：

 

Q: Will I be able to access my EBS snapshots using the regular Amazon S3 APIs?

 

No, EBS snapshots are only available through the Amazon EC2 APIs.

 

 

FALSE. A Dedicated Host is required if you'd like to use your existing Windows Server licenses. cannot be "Amazon EC2 shared tenancy instance"

 

D. S3-RRS is most often used with reproducible objects.

 

S3, AMI 都是区域性的。

 

Connection draining is enabled by default and provides a period of time for existing connections to close cleanly

 

You cannot edit a launch configuration once defined

The launch configuration will have been created with detailed monitoring enabled which is chargeable. You will need to recreate the launch configuration with basic monitoring enabled

 

Which AWS services can be used to automate the release process of your serverless Lambda applications? (choose 2)

A. AWS CodePipeline

C. AWS CodeDeploy

 

Application Load Balancer 最適合用來處理HTTP 與HTTPS 流量的負載平衡

Load Balancer 在連線層(Layer 4) 負載平衡器會嘗試開啟接聽程式設定中指定之連接埠上所選目標的 TCP 連線

 

When you launch an instance into a default VPC, we provide the instance with public and private DNS hostnames that correspond to the public IPv4 and private IPv4 addresses for the instance

 

A task definition is a text file in JSON format that describes one or more containers, up to a maximum of 10

 

时段低于 60 秒的数据点可保留 3 个小时。这些数据点是高分辨率自定义指标。

时段为 60 秒（1 分钟）的数据点可保留 15 天

时段为 300 秒（5 分钟）的数据点可保留 63 天 

时段为 3600 秒（1 小时）的数据点可保留 455 天（15 个月）

 

Access logging is an optional feature of Elastic Load Balancing that is disabled by default. After you enable access logging for your load balancer, Elastic Load Balancing captures the logs and stores them in the Amazon S3 bucket that you specify as compressed files. You can disable access logging at any time.

Amazon S3 Server Access Logging