The provided configuration is for a routing instance named VPN-A on a Juniper PE (Provider Edge) router. Let's break it down:
* Instance Type: VRF
* The instance-type vrf; statement indicates that this is a Layer 3 VPN (L3VPN) using MPLS VPNs (RFC 4364 - BGP/MPLS IP VPNs).
* This confirms that Option D (A Layer 3 VPN is configured) is correct #.
* VRF Target and Interface Association
* The vrf-target target:64512:1234; defines the route target (RT) for importing and exporting VPN routes.
* The interface ge-0/0/1.0; binds this interface to the VRF.
* BGP Configuration for CE (Customer Edge) Peering
* The group CE section configures external BGP (EBGP) (type external;).
* The neighbor 10.0.0.1 is in AS 64512 (peer-as 64512;).
* The as-override; statement is used.
Evaluating the Answer Choices
# Option B: "This VPN connects customer sites that use the same AS number."
* The as-override; command allows multiple customer sites that use the same AS number (64512) to communicate over the service provider's MPLS network.
* Normally, BGP prevents routes with the same AS in the AS_PATH from being accepted. The as- override feature replaces the customer's AS number with the provider's AS, ensuring proper route advertisement.
# This statement is correct.
# Option A: "This VPN connects customer sites that use different AS numbers."
* If the customer sites had different AS numbers, there would be no need for as-override.
* The as-override feature is specifically used when all customer sites share the same AS number, ensuring that BGP routes are accepted.
# This statement is incorrect.
# Option C: "A Layer 2 VPN is configured."
* A Layer 2 VPN (L2VPN) configuration would typically use instance-type l2vpn; or EVPN/VPLS- related parameters (e.g., protocols l2vpn or protocols vpls).
* Since this configuration uses instance-type vrf; and BGP with a VRF target, it is clearly a Layer 3 VPN (L3VPN).
# This statement is incorrect.
# Option D: "A Layer 3 VPN is configured."
* The instance-type vrf; confirms this is an MPLS Layer 3 VPN (L3VPN).
* VRFs, BGP, and route targets (vrf-target) are specific to Layer 3 VPNs.
# This statement is correct.
# B. This VPN connects customer sites that use the same AS number.
# D. A Layer 3 VPN is configured.
Verification from Juniper Documentation:
* Juniper BGP/MPLS Layer 3 VPNs Guide confirms that instance-type vrf is used for L3VPNs.
* Juniper BGP Configuration Guide states that as-override is applied when customer sites use the same AS number.
* RFC 4364 (BGP/MPLS IP VPNs) explains how route targets and VRFs are used in L3VPN deployments.