Quick Answer
The answer is GRE, or Generic Routing Encapsulation, because it is the technology most directly associated with creating a logical tunnel between edge routers for site-to-site connectivity across an IP network. GRE works by encapsulating packets from one protocol inside IP packets, allowing the routers to treat the public internet as a virtual point-to-point link, effectively bridging two remote sites as if they were directly connected. On the CCNA 200-301 v2 exam, this question tests your understanding of tunneling fundamentals versus other WAN technologies like IPsec or MPLS; a common trap is confusing GRE with IPsec, but remember that GRE provides the tunnel itself while IPsec adds encryption. A helpful memory tip is to think of GRE as the “envelope” that carries any payload across the network, making it the go-to for simple site-to-site logical tunnels.
This 200-301 practice question tests your understanding of ip routing. Read the scenario carefully and evaluate each option against the stated constraints before committing to an answer. A key principle to apply: gRE creates a logical point-to-point tunnel by encapsulating packets inside IP headers to transport them across an IP network transparently.. Once you have made your selection, read the full explanation to reinforce the concept and understand why each distractor is designed to mislead on exam day.
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?
GRE
This is correct because GRE is commonly used to create logical tunnels across IP networks.
PortFast
Why wrong: This is wrong because PortFast is an STP edge-port feature.
DHCP relay
Why wrong: This is wrong because DHCP relay forwards client broadcast requests and is not a general site-to-site tunnel technology.
Root guard
Why wrong: This is wrong because root guard is an STP topology-protection feature.
Answer choices
Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.
Correct answer & explanation
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.
Key principle: GRE creates a logical point-to-point tunnel by encapsulating packets inside IP headers to transport them across an IP network transparently.
Answer analysis
For each option: why learners choose it and why it is or isn't the right answer here.
GRE
Why this is correct
This is correct because GRE is commonly used to create logical tunnels across IP networks.
Related concept
GRE creates a logical point-to-point tunnel by encapsulating packets inside IP headers to transport them across an IP network transparently.
PortFast
When this WOULD be correct
If the question asked about optimizing switch port behavior in a network where rapid connectivity is needed for end devices, PortFast would be the correct answer. For example, a scenario involving a network with multiple switches where minimizing downtime during network topology changes is critical would validate its use.
DHCP relay
Why it's wrong here
This is wrong because DHCP relay forwards client broadcast requests and is not a general site-to-site tunnel technology.
When this WOULD be correct
If the question asked about connecting clients to a DHCP server located on a different subnet, where the relay agent is required to forward DHCP messages, then DHCP relay would be the correct answer. This scenario focuses on DHCP functionality rather than tunneling.
Root guard
Why it's wrong here
This is wrong because root guard is an STP topology-protection feature.
When this WOULD be correct
If the exam question asked about securing the spanning tree topology in a network with multiple switches, where preventing rogue switches from becoming the root bridge is critical, then root guard would be the correct answer. This scenario would focus on maintaining network stability rather than tunneling.
Option-by-option analysis
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.
Why this is correct
This is correct because GRE is commonly used to create logical tunnels across IP networks.
Why this is wrong here
PortFast is a Cisco switch feature that immediately transitions a port to the forwarding state, bypassing the Spanning Tree Protocol (STP) listening and learning phases. It is used for access ports connected to end devices, not for creating tunnels between sites.
★ When this WOULD be the correct answer
If the question asked about optimizing switch port behavior in a network where rapid connectivity is needed for end devices, PortFast would be the correct answer. For example, a scenario involving a network with multiple switches where minimizing downtime during network topology changes is critical would validate its use.
Why candidates choose this
Students might confuse PortFast with a feature that speeds up network connectivity, but it is unrelated to tunneling or site-to-site connections.
Why this is wrong here
DHCP relay is a feature that forwards DHCP broadcast requests from clients on one subnet to a DHCP server on another subnet. It does not create a logical tunnel between sites; it simply helps with IP address assignment across subnets.
★ When this WOULD be the correct answer
If the question asked about connecting clients to a DHCP server located on a different subnet, where the relay agent is required to forward DHCP messages, then DHCP relay would be the correct answer. This scenario focuses on DHCP functionality rather than tunneling.
Why candidates choose this
The term 'relay' might suggest forwarding traffic between networks, leading students to think it could be used for site-to-site connectivity, but it is not a tunneling technology.
Why this is wrong here
Root guard is a Spanning Tree Protocol (STP) feature that prevents a switch port from becoming the root port, enforcing the root bridge location. It is used to protect the STP topology, not to create tunnels between sites.
★ When this WOULD be the correct answer
If the exam question asked about securing the spanning tree topology in a network with multiple switches, where preventing rogue switches from becoming the root bridge is critical, then root guard would be the correct answer. This scenario would focus on maintaining network stability rather than tunneling.
Why candidates choose this
The word 'guard' might imply a security or connectivity feature, but root guard is specifically for STP and has no role in tunneling.
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?”
Common exam traps
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.
Detailed technical explanation
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.
Key takeaway
GRE creates a logical point-to-point tunnel by encapsulating packets inside IP headers to transport them across an IP network transparently.
Real-world example
A small business has 20 workstations on the 192.168.1.0/24 network and one public IP from its ISP. The router uses PAT (NAT overload) so all 20 devices share one public address using different source ports. NAT questions test whether you understand the four address terms and which direction each translation applies.
What to study next
Review gRE creates a logical point-to-point tunnel by encapsulating packets inside IP headers to transport them across an IP network transparently., then practise related 200-301 questions on the same topic to reinforce the concept.
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FAQ
IP Routing — This question tests IP Routing — GRE creates a logical point-to-point tunnel by encapsulating packets inside IP headers to transport them across an IP network transparently..
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.
Review gRE creates a logical point-to-point tunnel by encapsulating packets inside IP headers to transport them across an IP network transparently., then practise related 200-301 questions on the same topic to reinforce the concept.
GRE creates a logical point-to-point tunnel by encapsulating packets inside IP headers to transport them across an IP network transparently.
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Last reviewed: May 17, 2026
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