Question 1hardmultiple choice
Full question →hardmultiple choiceObjective-mapped
A company wants to connect two sites across an IP network by creating a logical tunnel between the edge routers. Which technology is most directly associated with that requirement?
Answer choices
Why each option matters
Good practice is not just finding the correct option. The wrong answers often show the exact trap the exam wants you to fall into.
A
Best answer
GRE
This is correct because GRE is commonly used to create logical tunnels across IP networks.
B
Distractor review
PortFast
This is wrong because PortFast is an STP edge-port feature.
C
Distractor review
DHCP relay
This is wrong because DHCP relay forwards client broadcast requests and is not a general site-to-site tunnel technology.
D
Distractor review
Root guard
This is wrong because root guard is an STP topology-protection feature.
Common exam trap
Common exam trap: answer the scenario, not the keyword
A common exam trap is mistaking GRE for unrelated Cisco features like PortFast or DHCP relay. PortFast is a Spanning Tree Protocol optimization for edge ports and does not create tunnels. DHCP relay forwards DHCP requests and is unrelated to site-to-site connectivity. Another trap is confusing GRE with security features like IPsec; GRE itself does not encrypt traffic but only encapsulates it. Candidates might also overlook that GRE tunnels require proper MTU handling to avoid fragmentation issues, which can cause connectivity problems if ignored.
Technical deep dive
How to think about this question
Generic Routing Encapsulation (GRE) is a tunneling protocol used to encapsulate a wide variety of network layer protocols inside virtual point-to-point links over an IP network. GRE creates a logical tunnel between two endpoints, allowing packets to be encapsulated and sent across an intermediate IP network as if they were directly connected. This encapsulation supports protocols that might not be natively routable over the underlying network, enabling site-to-site connectivity and protocol transport. In Cisco networking and the CCNA context, GRE tunnels are configured on edge routers to establish a virtual link between remote sites. The routers encapsulate the original packets inside GRE headers and IP headers, forwarding them through the existing IP infrastructure. This method is often combined with IPsec for encryption but GRE itself focuses on encapsulation and tunneling. The decision to use GRE is based on the need for a logical tunnel that can carry multiple protocols transparently across an IP backbone. A common exam trap is confusing GRE with other unrelated technologies such as PortFast or DHCP relay. GRE is not a switching feature or a DHCP forwarding mechanism; it specifically creates tunnels. In practical deployments, GRE tunnels can introduce overhead and require proper MTU configuration. Understanding GRE’s role in encapsulation and tunneling helps avoid misapplying other Cisco features that do not provide site-to-site logical tunnels.
KKey Concepts to Remember
- GRE creates a logical point-to-point tunnel by encapsulating packets inside IP headers to transport them across an IP network transparently.
- GRE tunnels allow multiple Layer 3 protocols to be carried over an IP network, enabling site-to-site connectivity beyond simple IP routing.
- Cisco routers use GRE to establish virtual interfaces that behave like direct links between remote sites for routing and protocol transport.
- GRE encapsulation adds overhead, so MTU size must be adjusted to prevent fragmentation on the tunnel path.
- PortFast is an STP feature that immediately transitions a switch port to forwarding state and does not create tunnels or affect routing.
- DHCP relay forwards DHCP broadcast requests between clients and servers and does not provide any tunneling or site-to-site connectivity.
- Root guard protects the Spanning Tree Protocol topology by preventing a port from becoming a root port but does not create tunnels.
- GRE tunnels can be combined with IPsec to provide secure encrypted tunnels, but GRE alone does not provide encryption.
TExam Day Tips
- Watch for words such as best, first, most likely and least administrative effort.
- Review why wrong options are wrong, not only why the correct option is correct.
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More questions from this exam
Keep practising from the same exam bank, or move into a focused topic page if this question exposed a weak area.
Question 1
A router learns the same prefix from both OSPF and EIGRP. Which route is installed by default?
Question 2
A router shows this output: R1#show ip ospf neighbor Neighbor ID Pri State Dead Time Address Interface 10.1.1.2 1 FULL/DR 00:00:34 192.168.12.2 GigabitEthernet0/0 10.1.1.3 1 2WAY/DROTHER 00:00:39 192.168.12.3 GigabitEthernet0/0 Which statement is correct?
Question 3
What is the OSPF metric called?
Question 4
A non-root switch has two uplinks toward the root bridge. One path has a lower total STP cost than the other. What role will the lower-cost uplink have?
Question 5
A router interface applies this ACL inbound: 10 deny tcp any any eq 80 20 permit ip any any A user reports that web browsing to a server by IP address fails, but ping works. Which statement best explains the behavior?
Question 6
A router learns route 198.51.100.0/24 from OSPF with AD 110 and also has a static route to the same prefix configured with AD 150. Which route is installed?
FAQ
Questions learners often ask
What does this 200-301 question test?
GRE creates a logical point-to-point tunnel by encapsulating packets inside IP headers to transport them across an IP network transparently.
What is the correct answer to this question?
The correct answer is: GRE — GRE is the most directly associated technology because it creates a logical tunnel between routers across an existing IP network. In practical terms, it allows the routers to treat the path as a virtual point-to-point connection for encapsulated traffic. The question is specifically about tunneling between sites, not about plain routing, management, or switching behavior.
What should I do if I get this 200-301 question wrong?
Then try more questions from the same exam bank and focus on understanding why the wrong options are tempting.
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