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etcd is designed to withstand(resilient) machine failures. An etcd cluster automatically recovers from any number of temporary failures (e.g., machine reboots) and tolerates up to (N-1)/2 permanent failures for a cluster of N members. When a member permanently fails, whether due to hardware failure or disk corruption, it loses access to the cluster. If the cluster permanently loses more than (N-1)/2 members then it disastrously fails, irrevocably losing quorum.

For example, if a three-node cluster suffered two simultaneous and unrecoverable machine failures, it would be normally impossible for the cluster to restore quorum and continue functioning.

Once a quorum is lost, the cluster cannot reach consensus and therefore cannot continue accepting updates. 

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It is a straightforward theoretical question.

If the question is asked for "temporary failures" - Then etcd cluster can automatically recover from it any no. of times.

Here the question is asked for "permanent failures" - An etcd cluster automatically recovers from temporary failures (e.g., machine reboots) and tolerates up to (N-1)/2 permanent failures for a cluster of N members. 

• Maps a fixed IP address to a logical group of pods. Generally, used for internal pod communication.
• Service has a static IP Address with a DNS name, that can be attached to Pod. SERVICE also works as a load balancer.
• The lifecycle of Pods & Service is not connected. So even if Pod dies, & replaced by a new Pod, it gets a new IP address, and it still has the same service through which they can communicate.

• In the real world, we don't directly deal with pods, we deal with an abstraction layer over pods known as Deployment.
• DEPLOYMENT is an Abstraction layer over PODS, which makes it more convenient to interact with the pods & replicate them and do some other configuration.
• Details on how to roll out (or roll back) across versions of your application.

• A thin wrapper around one or more containers
• The smallest unit of Kubernetes(K8s)
• Abstraction layer over the container
• Usually 1 app container per pod
• Epithermal

• Ensures that a specified number of pod replicas are running at any one time.
• In other words, it makes sure that a pod or a homogeneous set of pods is always up and available.

"Service" - clearly signifies for svc command.

• Defines the format of data on the network.

• Decides which physical path the data will take.

• Maintains connections & responsible for controlling ports & sessions.

• Human Computer Interaction layer, where apps can access network services.
• Used by end-user software such as web browsers and email clients.
• Provides protocols that allow software to send and receive information and present meaningful data to users.
• Examples of application layer protocols are the Hypertext Transfer Protocol (HTTP), File Transfer Protocol (FTP), Post Office Protocol (POP), Simple Mail Transfer Protocol (SMTP), and Domain Name System (DNS).
• Thus,Load Balancer which efficiently distributing incoming network traffic across a group of backend servers is based on layer 7.

• In order for the Ingress resource to work, the cluster must have an ingress controller running.
• Unlike other types of controllers which run as part of the kube-controller-manager binary, Ingress controllers are not started automatically with a cluster.
• Kubernetes as a project supports and maintains AWS, GCE, and nginx ingress controllers.
• Layer 7(Application layer) is Human Computer Interaction layer, where apps can access network services.