CCNA IP Routing Practice Question
Exhibit
interface Tunnel0 ip address 10.10.10.1 255.255.255.252 tunnel source GigabitEthernet0/0 tunnel destination 198.51.100.2
An administrator configures a GRE tunnel interface on a router with the following: interface Tunnel0, tunnel source GigabitEthernet0/0, tunnel destination 192.168.2.2. What is the main purpose of this configured tunnel?
⚠ Common exam trap
A frequent exam trap is confusing GRE tunnels with encryption or automatic routing protocol establishment. Candidates often assume that because GRE creates a tunnel, it also encrypts traffic or automatically enables protocols like BGP. However, GRE only encapsulates packets and does not provide confidentiality or integrity. Encryption requires pairing GRE with IPsec. Additionally, routing protocols must be explicitly configured over the tunnel interface; the tunnel itself does not initiate or enable them. Misreading the tunnel configuration as PPP authentication or wireless security is another common pitfall, as GRE operates at Layer 3 and is unrelated to those technologies.
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
✓
It creates a logical tunnel across another network.
GRE is a tunneling mechanism used to carry one type of traffic over another network path by encapsulating packets. In practical terms, the configuration creates a logical tunnel between endpoints so traffic can cross an underlying IP network as if a virtual path existed between them. The key point is that GRE is about tunneling, not encryption by itself. This distinction matters because people often assume tunnels automatically imply encryption. GRE by itself does not provide that.
Answer analysis
Option-by-option breakdown
For each option: why learners choose it and why it is or isn't the right answer here.
- ✓
It creates a logical tunnel across another network.
Why this is correct
The configured tunnel interface takes the original packet and wraps it in a new IP header, with the tunnel source and destination addresses serving as the endpoints of that encapsulation. This creates a logical, virtual path that traverses an underlying physical or routed network, allowing traffic from two remote sites to appear as if they are directly connected even though they are separated by intermediate hops. Thus, the purpose is to establish an overlay network across another network, not to provide any security or link-level protocol function.
- ✗
It enables PPP authentication on a serial interface.
Why it's wrong here
PPP authentication is a data-link-layer feature used on serial interfaces, where protocols such as PAP or CHAP validate the peer after PPP encapsulation is enabled with 'encapsulation ppp'. The exhibit shows a tunnel interface, which is a virtual logical interface that encapsulates packets at Layer 3, and it has no relationship to serial encapsulation or the authentication handshake used on physical serial links. Therefore, the configuration is unrelated to enabling PPP authentication on a serial interface.
When this WOULD be correct
In a different question that asks about the configuration of a serial interface and its authentication methods, option B would be correct if the context involved enabling PPP authentication to secure data transmission over that interface.
- ✗
It configures WPA3 security for a wireless bridge.
Why it's wrong here
WPA3 is an authentication and encryption framework defined by the Wi-Fi Alliance for securing wireless LAN communications, typically using mechanisms like SAE to protect the handshake. The exhibit describes a Layer 3 tunnel created by configuring tunnel source and destination IP addresses, which is a routing and encapsulation function, not a wireless security setting. Because there is no mention of SSIDs, access points, or wireless security modes, the configuration cannot be implementing WPA3 on a wireless bridge.
When this WOULD be correct
This option would be correct in a question that asks about the security protocols used in a wireless network setup, specifically focusing on the implementation of WPA3 for securing a wireless bridge connection. For example, a question might ask, 'What security protocol is used to enhance the security of a wireless bridge?'
- ✗
It enables BGP between autonomous systems automatically.
Why it's wrong here
BGP is an exterior gateway protocol that forms TCP peering sessions on port 179 using explicit 'neighbor' commands, and it requires manual configuration of autonomous system numbers and policies to exchange routing information. While a tunnel can carry BGP traffic between routers, it does not automatically trigger BGP to establish a session or discover neighbors—the tunnel merely provides a virtual link, not a routing protocol mechanism. In short, the tunnel's purpose is to create a logical path, not to enable BGP between autonomous systems.
When this WOULD be correct
If the exam question specifically asked about the configuration of a network that uses BGP to connect multiple autonomous systems over a tunnel, then this option could be correct. For example, a question might describe a scenario where BGP is being used to facilitate communication between two ISPs over a GRE tunnel.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 200-301 exam frequently reuses these exact scenarios with slightly different constraints.
✓It creates a logical tunnel across another network.Correct answer▾
Why this is correct
The configured tunnel interface takes the original packet and wraps it in a new IP header, with the tunnel source and destination addresses serving as the endpoints of that encapsulation. This creates a logical, virtual path that traverses an underlying physical or routed network, allowing traffic from two remote sites to appear as if they are directly connected even though they are separated by intermediate hops. Thus, the purpose is to establish an overlay network across another network, not to provide any security or link-level protocol function.
✗It enables PPP authentication on a serial interface.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because the question specifically asks about the purpose of a configured tunnel, which relates to creating a logical connection across networks, not about enabling PPP authentication, which is specific to serial interfaces.
★ When this WOULD be the correct answer
In a different question that asks about the configuration of a serial interface and its authentication methods, option B would be correct if the context involved enabling PPP authentication to secure data transmission over that interface.
Why candidates choose this
Candidates may be tempted by this option due to familiarity with PPP authentication in networking, leading them to mistakenly associate it with tunnel configurations without considering the specific context of the question.
✗It configures WPA3 security for a wireless bridge.Wrong answer — click to see why▾
Why this is wrong here
This option is wrong because the question specifically asks about a tunnel configuration, which is unrelated to WPA3 security settings for wireless networks. WPA3 pertains to securing wireless communications, not tunneling protocols.
★ When this WOULD be the correct answer
This option would be correct in a question that asks about the security protocols used in a wireless network setup, specifically focusing on the implementation of WPA3 for securing a wireless bridge connection. For example, a question might ask, 'What security protocol is used to enhance the security of a wireless bridge?'
Why candidates choose this
Candidates may find this option tempting because they might confuse the concept of tunneling with securing wireless connections, especially if they have encountered both topics in their studies and are unsure of the specific context of the question.
✗It enables BGP between autonomous systems automatically.Wrong answer — click to see why▾
Why this is wrong here
This option is incorrect because the configured tunnel's primary purpose is to create a logical tunnel across another network, not to enable BGP between autonomous systems. BGP configuration typically does not involve tunneling directly.
★ When this WOULD be the correct answer
If the exam question specifically asked about the configuration of a network that uses BGP to connect multiple autonomous systems over a tunnel, then this option could be correct. For example, a question might describe a scenario where BGP is being used to facilitate communication between two ISPs over a GRE tunnel.
Why candidates choose this
Candidates might find this option tempting because BGP is commonly associated with network routing and can be involved in complex network setups, leading them to mistakenly connect it with tunnel configurations.
Analysis generated from the official 200-301blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
Visual reference
Quick reference
Routing Protocol Comparison
| Protocol | Metric | Max Hops | Algorithm | Type |
|---|---|---|---|---|
| RIP v2 | Hop count | 15 | Bellman-Ford | Distance vector |
| OSPF | Cost (bandwidth) | Unlimited | Dijkstra (SPF) | Link state |
| EIGRP | Composite metric | Unlimited | DUAL | Hybrid |
| IS-IS | Cost | Unlimited | Dijkstra | Link state |
| BGP | Policy / attributes | Unlimited | Path vector | Path vector |
RIP's 15-hop limit makes it unsuitable for large networks. OSPF and EIGRP dominate modern enterprise deployments.
Go deeper
Related to this question
Learn chapter
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Key term
GRE
Generic Routing Encapsulation is a tunneling protocol that wraps packets of one protocol inside another protocol to transport them across an intermediary network.
Key term
CAN
A CAN (Controller Area Network) is a robust vehicle bus standard designed to allow microcontrollers and devices to communicate with each other without a host computer.
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JA
Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 200-301 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 200-301 exam.