CKA Services and Networking Practice Question
You have a kube-proxy running in ipvs mode. Which of the following is true about IPVS?
⚠ Common exam trap
It's easy for candidates to confuse IPVS with iptables, assuming IPVS still relies on iptables rules for service discovery, when in fact IPVS uses a separate kernel-level mechanism with its own scheduling algorithms.
Answer choices
Why each option matters
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
✓
IPVS supports multiple load balancing algorithms.
IPVS (IP Virtual Server) supports multiple load balancing algorithms, such as round-robin, least-connection, source-hashing, and others, which is a key advantage over iptables mode. This allows kube-proxy to distribute traffic across pods more flexibly and efficiently, especially in high-traffic environments.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
IPVS supports multiple load balancing algorithms.
Why this is correct
IPVS (IP Virtual Server) is a kernel-level transport-layer load balancer that exposes multiple scheduling algorithms, including round-robin (rr), least-connections (lc), destination hashing (dh), and source hashing (sh). kube-proxy in IPVS mode programs these algorithms into the kernel, allowing operators to select a traffic distribution strategy that best fits their workload instead of being limited to iptables' simple random or default behavior.
- ✗
IPVS uses iptables rules for service discovery.
Why it's wrong here
IPVS does not use iptables rules for service discovery; it leverages its own kernel modules and netfilter hooks to manage virtual services and real servers. While iptables may still be used for auxiliary tasks such as masquerading or hairpin edge cases, the actual service discovery and load-balancing decisions happen inside IPVS kernel tables, not through iptables rule chains.
- ✗
IPVS is the default kube-proxy mode since Kubernetes 1.0.
Why it's wrong here
IPVS has never been the default kube-proxy mode since Kubernetes 1.0. The default mode has long been iptables, and IPVS was introduced later, becoming beta in v1.8 and generally available in v1.11, but even then it required an explicit flag (--proxy-mode=ipvs) or configuration to enable. Kubernetes does not set IPVS as the default, so this statement confuses an optional capability with the historical default behavior.
- ✗
IPVS cannot handle large numbers of services.
Why it's wrong here
IPVS scales far better than iptables for large numbers of services because it uses hash-based lookup tables with O(1) complexity, whereas iptables traverses a linear chain of rules whose cost grows with each added rule. In fact, IPVS was adopted by kube-proxy specifically to address the performance degradation of iptables in clusters with thousands of Services. Therefore, stating that IPVS cannot handle large numbers of Services is exactly opposite to its design purpose and known scalability advantages.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
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