MCQs

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1. What is the primary purpose of Multipoint Generic Routing Encapsulation (mGRE) in networking?
   a. To allow a single tunnel interface to support multiple endpoints
   b. To encrypt network data
   c. To limit communication to point-to-point topologies
   d. To replace dynamic routing protocols
   Answer: a
   cbtnuggets+2
2. Which protocol is commonly used alongside mGRE for route resolution in large-scale VPN design?
   a. NHRP
   b. SNMP
   c. TCP
   d. FTP
   Answer: a
   pluralsight+1
3. Regular GRE tunnels differ from mGRE by being:
   a. Always encrypted
   b. Point-to-point only
   c. Scalable for large networks
   d. Compatible with multicast by default
   Answer: b
   notes.networklessons+1
4. mGRE tunnels are especially useful in what type of network topology?
   a. Bus
   b. Mesh or hub-and-spoke
   c. Star
   d. Ring
   Answer: b
   exam-labs+1
5. Which mGRE network node acts as the main routing information exchange and data forwarding center?
   a. NHRP Client (NHC)
   b. NHRP Server (NHS)
   c. DNS Proxy
   d. DHCP Relay
   Answer: b
   h3c
6. What advantage does mGRE offer over traditional GRE in VPN scalability?
   a. Automatic encryption
   b. Dynamic addition of endpoints
   c. Built-in firewall
   d. Higher throughput by default
   Answer: b
   exam-labs
7. In an mGRE configuration, remote sites are typically referred to as:
   a. Servers
   b. Hubs
   c. Clients (NHC)
   d. Proxies
   Answer: c
   h3c
8. One common pairing with mGRE to ensure secure data transmission is:
   a. SSL
   b. IPsec
   c. ARP
   d. HTTPS
   Answer: b
   exam-labs+1
9. What is the minimal number of tunnel interfaces required on a router for mGRE to connect multiple endpoints?
   a. One
   b. Two
   c. Three
   d. Four
   Answer: a
   notes.networklessons+1
10. Which issue can arise if all remote mGRE traffic routes via a single hub?
    a. Hardware compatibility
    b. Congestion or single point of failure
    c. Loopback errors
    d. Reduced encryption overhead
    Answer: b
    exam-labs
11. What command on a Cisco router enables mGRE on a tunnel interface?
    a. tunnel mode gre multipoint
    b. enable tunnel-multipoint
    c. configure multipoint-gre
    d. gre multipoint enable
    Answer: a
    exam-labs
12. mGRE is not inherently secure because:
    a. GRE itself does not provide encryption
    b. It uses static NAT
    c. It disables routing protocols
    d. It only supports IPv6
    Answer: a
    exam-labs
13. NHRP, in relation to mGRE, is most similar in function to:
    a. ARP on Ethernet
    b. DNS for IP
    c. DHCP for subnets
    d. SNMP monitoring
    Answer: a
    pluralsight+1
14. Dynamic routing protocols often used with mGRE include:
    a. EIGRP and OSPF
    b. RIP and HTTP
    c. BGP and SMTP
    d. MPLS and FTP
    Answer: a
    exam-labs
15. Which of these is a typical troubleshooting step for mGRE tunnel interface issues?
    a. show interfaces Tunnel 0
    b. check dns cache
    c. verify nat pool
    d. run http diagnostics
    Answer: a
    exam-labs
16. The main benefit of using a single mGRE interface per device is:
    a. Simpler network management
    b. Multi-layer encryption
    c. Traffic shaping
    d. Decreased compatibility
    Answer: a
    exam-labs
17. In mGRE, when must dynamic IP-to-endpoint mappings occur?
    a. When endpoints have dynamic public IP addresses
    b. When static routing is used
    c. When all endpoints share an IP
    d. When encryption is not needed
    Answer: a
    h3c
18. Which of the following statements about GRE and mGRE is accurate?
    a. Only mGRE can support broadcast/multicast traffic
    b. mGRE was introduced before GRE
    c. Both can transport multicast, but mGRE is scalable
    d. GRE supports more nodes per tunnel than mGRE
    Answer: c
    exam-labs
19. When using mGRE in a hub-and-spoke model, spokes:
    a. Only communicate through the hub by default
    b. Are unable to use IPsec
    c. Do not participate in routing
    d. Must be physically connected
    Answer: a
    h3c
20. The process where NHCs register their public and private addresses is called:
    a. Tunnel registration
    b. Dynamic resolution
    c. NAT traversal
    d. OSPF adjacency
    Answer: a
    h3c
21. To verify routing across an mGRE tunnel you would most likely use:
    a. show ip route
    b. ping 127.0.0.1
    c. show version
    d. traceroute
    Answer: a
    exam-labs
22. Which scenario best illustrates the use of mGRE?
    a. A company with many branch offices uses a single logical tunnel to connect all branches via a central data center
    b. A static VLAN setup in a LAN
    c. A campus network with only local devices
    d. Interconnecting two home Wi-Fi routers
    Answer: a
    exam-labs
23. mGRE mitigates this complexity as compared to GRE:
    a. Number of tunnels needed per endpoint
    b. Routing protocol support
    c. Encryption method
    d. NAT translation
    Answer: a
    exam-labs
24. Which technology is commonly layered on top of mGRE for VPN deployment?
    a. DMVPN
    b. SNMP
    c. SSL VPN
    d. FTP tunneling
    Answer: a
    thinkpalm+1
25. mGRE is particularly helpful in what growth scenario?
    a. Adding numerous remote locations
    b. Decreasing the routing table size
    c. Swapping cables
    d. Shortening cable length
    Answer: a
    exam-labs
26. What key step must be completed for every mGRE remote site?
    a. Assign a unique tunnel IP address
    b. Use a static NAT pool
    c. Set up a separate VLAN
    d. Disable dynamic routing
    Answer: a
    exam-labs
27. If the mGRE tunnel MTU is misconfigured, which might occur?
    a. Packet fragmentation or loss
    b. DNS failure
    c. ARP flooding
    d. Spanning Tree loop
    Answer: a
    exam-labs
28. What is a core function of the NHRP protocol in mGRE configurations?
    a. Mapping tunnel IP to real (NBMA) IP address
    b. Encrypting the data stream
    c. Assigning MAC addresses
    d. Handling DNS queries
    Answer: a
    h3c
29. If a network must remain operational in the event of a hub failure, what should be implemented in the mGRE design?
    a. Hub redundancy
    b. Static ARP entries
    c. DHCP snooping
    d. Broadcast storm control
    Answer: a
    exam-labs
30. Which command displays the status of an mGRE tunnel in Cisco IOS?
    a. show interfaces tunnel <number>
    b. show logging
    c. show run vlan
    d. show mac
    Answer: a
    exam-labs
31. What benefit do dynamic routing protocols bring to mGRE?
    a. Automatic route updates as network changes
    b. Automated encryption setup
    c. NAT translation
    d. VLAN segmentation
    Answer: a
    exam-labs
32. When configuring an mGRE tunnel interface on a Cisco hub, what must always be included?
    a. tunnel mode gre multipoint
    b. ip nat inside
    c. spanning-tree portfast
    d. no shutdown
    Answer: a
    exam-labs
33. Which configuration is valid for an mGRE interface on a hub router?
    a. interface Tunnel0, tunnel mode gre multipoint
    b. vlan 10, ip helper-address
    c. interface Serial0/0, encapsulation ppp
    d. interface FastEthernet0/0, switchport trunk
    Answer: a
    exam-labs
34. A drawback of mGRE when improperly planned is:
    a. Centralized traffic bottlenecks
    b. Extra physical cabling
    c. Too many VLANs
    d. Automatic encryption
    Answer: a
    exam-labs
35. To scale an mGRE network securely, organizations often pair mGRE with:
    a. IPsec encryption
    b. RIP v2
    c. Proxy ARP
    d. ISDN BRI
    Answer: a
    h3c+1
36. In mGRE deployments involving cloud, what is typically achieved?
    a. Seamless hybrid cloud networking
    b. Static network segments
    c. Public IP exhaustion
    d. Restriction to local traffic only
    Answer: a
    exam-labs
37. What does “tunnel mode gre multipoint” configure on a Cisco router?
    a. Enables multipoint capability for GRE tunnel
    b. Activates Layer 2 switching
    c. Sets up SNMP on the tunnel
    d. Allocates a NAT pool
    Answer: a
    exam-labs
38. Which network scenario is NOT a typical application for mGRE?
    a. Bridging remote branches over VPN
    b. Connecting multiple IoT device networks
    c. Large-scale campus LAN segment
    d. Hybrid cloud integration
    Answer: c
    exam-labs
39. An mGRE client that cannot forward data received from other mGRE nodes is referred to as:
    a. NHC
    b. NHS
    c. VLAN
    d. Gateway Proxy
    Answer: a
    h3c
40. For mGRE, what best describes the “full-mesh” model?
    a. NHCs can establish dynamic tunnels between each other for direct communication
    b. All devices use one VLAN
    c. Only one spoke connects at a time
    d. Static routing exclusively governs all sites
    Answer: a
    h3c
41. Which feature enhances mGRE tunnel reliability in enterprise use cases?
    a. Redundant hub routers
    b. Single static IP range
    c. Multihop OSPF only
    d. IP phone registration
    Answer: a
    exam-labs
42. What happens if the central hub in mGRE fails and there is no redundancy?
    a. All remote site connectivity is lost
    b. All sites switch to multicast
    c. The hub is ignored by other routers
    d. Routing becomes static
    Answer: a
    exam-labs
43. mGRE is most often used in conjunction with which security technology in DMVPN?
    a. IPsec
    b. SSL VPN
    c. MACsec
    d. WPA2
    Answer: a
    thinkpalm+1
44. If a remote branch’s public IP changes, how does mGRE maintain tunnel connectivity?
    a. Through dynamic NHRP updates
    b. By restarting the hub router
    c. Using static NHRP tables
    d. Only manual reconfiguration
    Answer: a
    h3c
45. Which technology, when used with mGRE, allows dynamic peer discovery?
    a. Next Hop Resolution Protocol (NHRP)
    b. Static ARP tables
    c. DNS reverse zone
    d. DHCP Option 82
    Answer: a
    pluralsight+1
46. What kind of address is mapped using NHRP in an mGRE tunnel?
    a. Tunnel IP to NBMA IP address
    b. MAC to IPv4
    c. VLAN ID to port
    d. IPv6 only
    Answer: a
    h3c
47. Which protocol is recommended for routing over mGRE tunnels in large dynamic environments?
    a. OSPF
    b. RIP version 1
    c. L2TP
    d. FTP
    Answer: a
    exam-labs
48. mGRE deployment in healthcare often addresses:
    a. Securely connecting remote clinics to the central data center
    b. Only providing public Wi-Fi
    c. Limiting multicast traffic
    d. Restricting patient access
    Answer: a
    exam-labs
49. Which command on a Cisco device checks mGRE tunnel encapsulation?
    a. show tunnel <number>
    b. show mac address-table
    c. show vlan brief
    d. ping
    Answer: a
    exam-labs
50. What best describes the role of a hub in mGRE VPN topology?
    a. Central aggregation and management point for all remote tunnel endpoints
    b. Standalone router with no remote access
    c. Edge router for Internet browsing only
    d. VLAN trunk manager
    Answer: a

1. https://www.cbtnuggets.com/blog/technology/networking/what-is-a-gre-multipoint-tunnel
2. https://notes.networklessons.com/mgre
3. https://www.exam-labs.com/blog/understanding-gre-multipoint-tunnels-a-comprehensive-guide-to-vpn-scalability
4. https://www.pluralsight.com/resources/blog/tech-operations/multipoint-gre-tunnel-introduction
5. https://www.h3c.com/en/d_202202/1553268_294551_0.htm
6. https://thinkpalm.com/blogs/introduction-dynamic-multipoint-virtual-private-network-dmvpn/
7. http://www.cisco.com/en/US/docs/ios-xml/ios/mp_l3_vpns/configuration/15-1s/ir-l3vpn-mgre.html
8. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/interface/configuration/xe-16-8/ir-xe-16-8-book/ir-mpls-vpnomgre-xe.pdf
9. https://www.firewall.cx/cisco/cisco-services-technologies/cisco-dmvpn-intro.html
10. https://thisbridgeistheroot.com/blog/dmvpn-deep-dive-nhrp-mgre-routing-scenarios
11. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/interface/configuration/xe-16/ir-xe-16-book/ip6-mgre-tunls.html
12. https://orhanergun.net/gre-tunnels-generic-routing-encapsulation-use-cases
13. https://docs.cradlepoint.com/r/dmvpn-configuration-guide/Configuring-mGRE
14. https://netseccloud.com/mgre-introduction
15. https://www.cisco.com/c/en/us/td/docs/ios-xml/ios/interface/configuration/xe-16/ir-xe-16-book/ir-mpls-vpnomgre-xe.pdf
16. https://netseccloud.com/mgre-deployment
17. https://orhanergun.net/dmvpn-point-to-point-gre-and-mgre
18. https://info.support.huawei.com/hedex/api/pages/EDOC1100331435/AEM10132/04/resources/dc/dc_fd_mpls-ldp_1021.html
19. https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/16-9/configuration_guide/rtng/b_169_rtng_9500_cg/configuring_unicast_and_multicast_over_point_to_multipoint_gre.html