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What is IP address?

The number that identifies a device (strictly, a network interface) on an IP network. An IPv4 address is 32 bits, written as four decimal numbers of 8 bits each such as 192.168.1.10; an IPv6 address is 128 bits, written in hexadecimal such as 2001:db8::1. It is split into a network part and a host part, with the boundary given by a subnet mask or CIDR notation such as /24. Private addresses used inside homes and companies (10.0.0.0/8, 172.16.0.0/12 and 192.168.0.0/16) are translated by NAT on the way to the internet.

Japanese name: IPアドレス

IP address appears in 25 practice questions across 7 topics, including Computer Networking Basics, Cloud and Container Basics, Cyber Attacks and Defense in Practice.

Field: Computer Networking Basics

Try it: questions about IP address

In Kubernetes, which of the following is the smallest unit that is deployed and managed, grouping one or more containers that share the same IP address and volumes?

  1. ANode
  2. BService
  3. CPod
Show answer and explanation

Answer: C. Pod

A Pod is the smallest unit Kubernetes places and runs. The containers in it share a network namespace, so they can talk to each other over localhost and can use the same volumes. Usually one Pod holds one application container, and helper containers, for example for forwarding logs, are sometimes added to the same Pod. Pods are disposable and get a new IP address when recreated, so they are normally managed indirectly through a Deployment or similar. A node is a machine on which Pods run, and a Service is a stable endpoint for several Pods.

In Kubernetes, a Pod gets a different IP address every time it is recreated. Which of the following resources lets other applications connect, through a name and address that do not change, to several Pods selected by labels, with the load spread across them?

  1. AConfigMap
  2. BService
  3. CPersistentVolume
Show answer and explanation

Answer: B. Service

A Service gives the set of Pods that match its label selector a virtual IP address and a DNS name that stay the same within the cluster, and distributes incoming traffic to those Pods. Even when Pods are replaced, clients only need to connect using the Service's name, so they do not need to know the Pods' addresses. To expose it outside the cluster, set the type to NodePort or LoadBalancer, or use an Ingress. A ConfigMap is a resource for configuration values, and a PersistentVolume is one for persistent storage.

IP address in the explanations

Questions that mention IP address (25)

  1. A container is started with the command above from the image nginx, a web server that listens on port 80. The host's IP address is 192.0.2.10, and there are no restrictions such as a firewall. Which of the following is the URL to use to reach this web server from a browser on another PC on the same network?
  2. In Kubernetes, which of the following is the smallest unit that is deployed and managed, grouping one or more containers that share the same IP address and volumes?
  3. In Kubernetes, a Pod gets a different IP address every time it is recreated. Which of the following resources lets other applications connect, through a name and address that do not change, to several Pods selected by labels, with the load spread across them?
  4. In the OSI reference model, which layer uses logical addresses such as IP addresses to relay packets between different networks until they reach their destination?
  5. A host has IP address 192.168.1.10 and subnet mask 255.255.255.0. What is the network address of the network it belongs to?
  6. In the network 192.168.5.0/26, how many IP addresses can be assigned to hosts (end devices or router interfaces)?
  7. A host has IP address 192.168.10.77/27. What is the broadcast address of its subnet?
  8. A full-service resolver (caching DNS server) with an empty cache looks up the IP address of www.example.com. In what order does it query servers?
  9. When a device obtains an IP address with DHCP, what is the correct order of messages?
  10. A web service saw a large number of login attempts from many different IP addresses, each using a different user's ID and password pair, and some succeeded. Many of the pairs tried matched ones leaked from other services. What is this attack called?
  11. What does 'IP (IP core)' mean in IC design?
  12. The choices omit the leading spaces of the line. In the session above, which of the following is the line printed by the last pipeline?
  13. Which statement about MAC addresses is correct?
  14. Compared with a hub (repeater hub), which correctly describes how an L2 switch operates?
  15. Home broadband routers perform NAPT (IP masquerading), a form of NAT (Network Address Translation). What does NAPT make possible?

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Related terms

Router DNS (Domain Name System) Subnet mask IP (Internet Protocol) URL (Uniform Resource Locator) Packet MAC address HTTP (Hypertext Transfer Protocol) DHCP HTTPS

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