mediumMultiple Select
Understanding NFV Architecture: VNFs and NFVI
Which two statements about Network Function Virtualization (NFV) architecture are true? (Choose two.)
Quick Answer
The correct answer is that Virtual Network Functions (VNFs) run on top of the NFV Infrastructure (NFVI). This is true because NFV architecture fundamentally decouples network functions from proprietary hardware, allowing VNFs—software implementations of services like routers or firewalls—to execute on the NFVI, which comprises standard compute, storage, and networking resources. On the ENCOR 350-401 exam, this concept tests your understanding of the separation between software and hardware layers; a common trap is confusing the NFV Orchestrator with the VNF Manager, as the Orchestrator handles broader lifecycle management across services, not just individual VNFs. Remember that NFVI is the physical and virtual resource pool, while VNFs are the software workloads running on it—think of NFVI as the stage and VNFs as the actors. A useful memory tip: VNFs sit on NFVI, just like apps sit on an operating system.
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
✓
NFV decouples network functions from proprietary hardware appliances.
Option A is correct because the core premise of NFV is decoupling network functions (such as firewalls, routers, and load balancers) from dedicated proprietary hardware appliances, allowing them to run as software on standard commercial off-the-shelf (COTS) servers. Option C is correct because in the ETSI NFV reference architecture, Virtual Network Functions (VNFs) execute on top of the NFV Infrastructure (NFVI), which provides the compute, storage, and network resources (often via a hypervisor) that the VNFs consume. Option B is incorrect because NFV explicitly aims to avoid dependence on specialized hardware such as ASICs, relying instead on general-purpose hardware, though acceleration technologies may optionally be used. Option D is incorrect because resource orchestration across multiple VIMs is the responsibility of the NFV Orchestrator (NFVO), while the VNF Manager handles the lifecycle management of VNF instances. Option E is incorrect because NFV does not mandate virtual machines; container-based and other cloud-native deployments are valid forms of VNF implementation.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
NFV decouples network functions from proprietary hardware appliances.
Why this is correct
NFV's core architectural principle separates network functions such as firewalls and routers from dedicated, vendor-specific appliances, letting them run as software on general-purpose servers. This decoupling directly satisfies the stem's requirement for a true statement about NFV architecture.
- ✗
NFV requires specialized ASICs to achieve line-rate performance.
Why it's wrong here
NFV deliberately replaces specialised hardware appliances with software running on commodity servers, so dedicated ASICs are not required. It tempts because line-rate performance is a genuine NFV concern, addressed instead through DPDK, SR-IOV and hardware acceleration offloads.
- ✓
Virtual Network Functions (VNFs) run on top of the NFV Infrastructure (NFVI).
Why this is correct
VNFs are deployed as software instances on the NFVI, which supplies the virtualised compute, storage and network resources they consume. This layered placement — VNF above NFVI — is precisely the architectural relationship the question asks you to confirm as true.
- ✗
The VNF Manager is solely responsible for resource orchestration across multiple VIMs.
Why it's wrong here
Resource orchestration across multiple VIMs sits with the NFV Orchestrator, not the VNF Manager, which handles VNF lifecycle management such as instantiation and scaling. It tempts because the VNF Manager does coordinate VNF-level resources, but only within a single VIM's scope.
- ✗
NFV mandates the use of virtual machines and cannot use container-based deployments.
Why it's wrong here
NFV's architectural framework is deployment-agnostic: the VNF and NFVI layers do not mandate virtual machines, so containerised VNFs are permitted. The claim of a VM mandate is therefore false. It tempts candidates because early NFV implementations were VM-centric, making VMs the correct choice when hardware-level isolation or legacy VNF packaging is required.
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Same concept, more angles
1 more way this is tested on 350-401
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. Which two statements about NFV architecture and components are true? (Choose two.)
medium- ✓ A.The NFV Infrastructure (NFVI) includes compute, storage, and networking resources that host VNFs.
- ✓ B.Virtual Network Functions (VNFs) are software implementations of network functions that run on virtualized infrastructure.
- C.Each VNF must be deployed on its own dedicated physical server to ensure performance isolation.
- D.The Virtualized Infrastructure Manager (VIM) is responsible for managing the lifecycle of VNFs.
- E.The NFV Orchestrator is primarily responsible for allocating virtual resources to VNFs.
Why A: Option A is correct because the NFV Infrastructure (NFVI) is defined by ETSI as the totality of hardware and software resources—compute (e.g., x86 servers), storage, and networking—on which VNFs are deployed and executed. Option B is correct because a Virtual Network Function (VNF) is precisely the software implementation of a network function (such as a firewall, router, or MME) that runs on virtualized infrastructure rather than on proprietary hardware. Option C is wrong because VNFs are designed to run on virtual machines or containers on shared, virtualized infrastructure, not on dedicated physical servers. Option D is wrong because VNF lifecycle management (instantiation, scaling, termination) is handled by the VNF Manager (VNFM), while the VIM manages the NFVI resources. Option E is wrong because allocating virtual resources to VNFs is the VIM's responsibility; the NFV Orchestrator focuses on end-to-end service orchestration and network service lifecycle management.
JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 350-401 practice question is part of Courseiva's free Cisco certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 350-401 exam.