A. PSNPs are used to acknowledge a received LSP.

D. PSNPs are used to request a missing LSP.

Answer DescriptionExplanation:

Intermediate System to Intermediate System (IS-IS) is a link-state routing protocol used to move information efficiently within a computer network. It uses a series of Protocol Data Units (PDUs) to manage the network's topology and ensure consistency across all routers in the network. Specifically, Link State PDUs (LSPs), Complete Sequence Number PDUs (CSNPs), and Partial Sequence Number PDUs (PSNPs) play crucial roles in this process.

1. PSNPs (Partial Sequence Number PDUs):

Acknowledge a received LSP: PSNPs are used to acknowledge the receipt of LSPs. When a router receives an LSP, it sends a PSNP back to the sender to confirm that the LSP has been received.

Request a missing LSP: PSNPs are also used to request missing LSPs. If a router identifies a missing LSP based on sequence numbers, it can send a PSNP to request the specific LSP from its neighbors.

2. CSNPs (Complete Sequence Number PDUs):

 Summarize LSPs: CSNPs are used to summarize all the LSPs known to a router. They are typically sent at regular intervals to provide a complete list of LSPs in a database. They are not used to acknowledge or request specific LSPs but provide an overview of all LSPs for database synchronization.

Based on this understanding, let's evaluate the statements:

A. PSNPs are used to acknowledge a received LSP.

Correct. PSNPs serve the purpose of acknowledging LSPs received from other routers.

B. CSNPs are used to acknowledge a received LSP.

Incorrect. CSNPs are not used for acknowledging LSPs; they are used to provide a summary of all LSPs.

C. CSNPs are used to request a missing LSP.

Incorrect. CSNPs are not used to request missing LSPs; this is the role of PSNPs.

D. PSNPs are used to request a missing LSP.

Correct. PSNPs are used to request specific missing LSPs when a router detects that it is missing information.

Conclusion:

The correct statements about IS-IS are:

A. PSNPs are used to acknowledge a received LSP.

D. PSNPs are used to request a missing LSP.

References:

Juniper Networks Documentation on IS-IS: [IS-IS Overview](https://www.juniper.net/documentation/en_US/junos/topics/concept/is-is-routing-overview.html)

RFC 1195, Use of OSI IS-IS for Routing in TCP/IP and Dual Environments: [RFC 1195](https://tools.ietf.org/html/rfc1195) which details the operation and use of IS-IS, including the roles of PSNPs and CSNPs.

A. A router with a priority of 10 wins the DIS election over a router with a priority of 1.
D. On the multi-access network, each router only forms an adjacency to the DIS.

A. Configure MSDP on each RP router.
B. Configure anycast PIM with the rp-set statement on each RP router.

B. A BGP peer does not require any configuration changes to become a route reflector client.

D. By default on PE-2, the remote site IDs are automatically assigned based on the order that you add the interfaces to the site configuration.

A. Internal L1 PDUs are flooded to the local area's L2 routers.
B. External L2 PDUs are flooded to all L2 routers in other areas.
D. Internal L1 PDUs are only flooded to the local area's L1 routers.

C. When the encapsulation is vLan-ccc or extended-vlan-ccc, the configured VLAN tag is included in the control plane LDP advertisement

D. When the encapsulation is ethemet-ccc, tagged and untagged frames are both accepted in the data plane.

Answer DescriptionExplanation:

The customer interface in an LDP-signaled pseudowire is the interface on the PE router that connects to the CE device. An LDP-signaled pseudowire is a type of Layer 2 circuit that uses LDP to establish a point-to-point connection between two PE routers over an MPLS network. The customer interface can have different encapsulation types depending on the type of traffic that is carried over the pseudowire. The encapsulation types are ethernet-ccc, vlan-ccc, extended-vlan-ccc, atm-ccc, frame-relay-ccc, ppp-ccc, cisco-hdlc-ccc, and tcc-ccc. Depending on the encapsulation type, the customer interface can accept or reject tagged or untagged frames in the data plane, and include or exclude VLAN tags in the control plane LDP advertisement. The following table summarizes the behavior of different encapsulation types:

A. LDP-signaled VPLS tunnels only support control bit 0.

C. BGP-signaled VPLS tunnels can use either RSVP or LDP between the PE routers.

Answer DescriptionExplanation:

https://www.juniper.net/documentation/us/en/software/nce/feature-guide-virtual-private-lan-service/topics/task/vpls-ldp-signaling-solutions.html

https://www.juniper.net/documentation/us/en/software/junos/vpn-l2/topics/concept/vpns-configuring-vpls-routing-instances.html#id-11510150__id-11568648