Service DNS Registration and Access

Questions and Answers

What happens first after posting the Service configuration to the API Server?

Cluster DNS notices the new Service

Endpoints created with Pod IPs

Configuration persisted to the cluster store (correct)

IPVS rules created

What is initiated when the Cluster DNS notices a new Service?

DNS records are created (correct)

Kube proxies stop pulling Service config

ClusterIP is assigned

DNS records are deleted

Which statement accurately describes the traffic flow when querying a Service Name?

Receive ClusterIP and send traffic to it (correct)

Traffic is sent directly to the container's IP

Query DNS for Service Name and receive Pod IP

Forward traffic to the default gateway of the container

What occurs if there is no route found when accessing a Service?

Traffic is forwarded to the Node Signup and view all the answers

What does the Node's kernel do when processing traffic destined for a Pod?

Rewrites the IP destination field to the Pod IP Signup and view all the answers

What is the role of Cluster DNS in the service access process?

It creates DNS records after a new Service is noticed. Signup and view all the answers

What action is taken when there is no route found to the ClusterIP?

Send traffic to the container's default gateway. Signup and view all the answers

What function do Kube proxies perform in the service registration process?

Pull the Service configuration. Signup and view all the answers

What happens during the processing phase by the Node's kernel?

IP packets are rewritten to reflect the Pod IP. Signup and view all the answers

Which of the following is NOT a step involved in DNS registration?

Cluster DNS creates IPVS rules. Signup and view all the answers

Study Notes

Service DNS Registration

Submitting Service configurations to the API Server utilizes a POST request.
Each Service is assigned a unique ClusterIP for internal communication.
Configuration details of the Service are stored persistently in the cluster’s storage system.
Endpoints are generated, associating Service with the IP addresses of active Pods.

Service Access

The Cluster DNS detects the introduction of a new Service and reacts accordingly.
DNS records are created automatically to facilitate Service discovery.
Kube proxies retrieve and maintain the most current Service configuration.
IPVS (IP Virtual Server) rules are established to manage traffic routing.
When a Service name is queried through DNS, a ClusterIP address is returned.
Network traffic is directed toward the obtained ClusterIP address.
If the route to ClusterIP is unavailable, traffic is sent to the container's default gateway.
Next, it is forwarded to the Node where the Service is hosted.
If there’s no route from the Node's perspective, it uses the Node's default gateway.
The Node's kernel processes and manages the incoming traffic.
TRAP rules activate under IPVS, essential for directing traffic efficiently.
The destination IP in packets is rewritten to the actual Pod IP to ensure proper delivery to the correct endpoint.

Service DNS Registration

Submitting Service configurations to the API Server utilizes a POST request.
Each Service is assigned a unique ClusterIP for internal communication.
Configuration details of the Service are stored persistently in the cluster’s storage system.
Endpoints are generated, associating Service with the IP addresses of active Pods.

Service Access

The Cluster DNS detects the introduction of a new Service and reacts accordingly.
DNS records are created automatically to facilitate Service discovery.
Kube proxies retrieve and maintain the most current Service configuration.
IPVS (IP Virtual Server) rules are established to manage traffic routing.
When a Service name is queried through DNS, a ClusterIP address is returned.
Network traffic is directed toward the obtained ClusterIP address.
If the route to ClusterIP is unavailable, traffic is sent to the container's default gateway.
Next, it is forwarded to the Node where the Service is hosted.
If there’s no route from the Node's perspective, it uses the Node's default gateway.
The Node's kernel processes and manages the incoming traffic.
TRAP rules activate under IPVS, essential for directing traffic efficiently.
The destination IP in packets is rewritten to the actual Pod IP to ensure proper delivery to the correct endpoint.

Description

This quiz covers the essentials of service DNS registration and access in Kubernetes. Questions focus on the API server configuration, DNS record creation, and the routing process for service traffic. Test your understanding of how services communicate within a Kubernetes cluster.