The Destination Guard feature helps in minimizing denial-of-service (DoS) attacks. It performs address resolutions only for those addresses that are active on the link, and requires the FHS binding table to be populated with the help of the IPv6 snooping feature.The feature enables the filtering of IPv6 traffic based on the destination address, and blocks the NDP resolution for destination addresses that are not found in the binding table. By default, the policy drops traffic coming for an unknown destination.
Reference:
5_0s_book/IPv6_Security.pdf

Let's see how the "logging synchronous" command affect the typing command:
Without this command, a message may pop up and you may not know what you typed if that message is too long. When trying to erase (backspace) your command, you realize you are erasing the message instead.

With this command enabled, when a message pops up you will be put to a new line with your typing command which is very

MPLS Layer-3 VPNs provide IP connectivity among CE sites * MPLS VPNs enable full-mesh, hub-andspoke, and hybrid IP connectivity * CE sites connect to the MPLS network via IP peering across PE-CE links * MPLS Layer-3 VPNs are implemented via VRFs on PE edge nodes * VRFs providing customer routing and forwarding segmentation * BGP used for signaling customer VPN (VPNv4) routes between PE nodes * To ensure traffic separation, customer traffic is encapsulated in an additional VPN label when forwarded in MPLS network * Key applications are layer-3 business VPN services, enterprise network segmentation, and segmented layer-3 Data Center access

LDP multicasts hello messages to a well-known UDP port (646) in order to discover neighbors. Once the discovery is accomplished, a TCP connection (port 646) is established and the LDP session begins. LDP keepalives ensure the health of the session. Thanks to the LDP session, LDP messages create the label mappings required for a FEC. Withdraw messages are used when FECs need to be torn down.