A.A sham-link is a logical link between PE routers that provides an OSPF adjacency between the PE routers and forwards customer traffic across it.
B.A sham-link is a logical link between PE routers that provides an OSPF adjacency between the PE routers and carries OSPF LSAs.
C.A sham-link is a logical link between PE routers that carries OSPF LSAs and forwards customer traffic across it.
D.A sham-link is a point-to-multipoint link that provides an OSPF adjacency between the PE routers and carries OSPF LSAs.
E.A sham-link is a point-to-multipoint link that provides an OSPF adjacency between the PE routers and forwards customer traffic across it.

A.Both RTA and RTB will do LSA7/5 translation，since they are both NSSA ABRs
B.RTA will do LSA7/5 translation，since it has the lower router ID
C.RTB will do LSA7/5 translation，since it has the higher router ID
D.The redistributing router will do LSA7/5 translation，since it is within the NSSA

A.It enables provider edge （PE） specific checks on a router when the OSPF process is associated with the VRF
B.It disables provider edge （PE） specific checks on a router when the OSPF process is associated with the VRF
C.It enables the exchange of the "VRF-Lite" capability when the OSPF adjacency is formed.
D.It disables the MPLS processing on the OSPF learned routes inside the VRF

A.OSPF external LSAs are automatically flooded into all OSPF areas, unlike type 7 LSAs, which require that redistribution be configured.
B.External LSAs (type 5) are automatically changed to type 1 LSAs at ASBRs.
C.Type 5 LSAs are route summaries describing routes to networks outside the OSPF Autonomous System.
D.External network LSAs (type 5) redistributed from other routing protocols into OSPF are not permitted to flood into a stub area

A.Before sending traffic, it must first join  multicast group 239.1.1.1 by sending an IGMPv2 membership report to the default router on the local subnet.
B.It must send an IGMPv2 Request to Send  packet and then wait for an IGMPv2 Clear to Send packet from the IGMPv2 querier router on the local subnet
C.It may begin transmitting multicast traffic to the group only when there is no other host transmitting to the group on the local subnet.
D.It may transmit multicast traffic to the group at any time. 

A.00000
B.12345
C.23456
D.65000
E.99999

A.a root port being transitioned to the blocking state
B.a port being assigned as a root port
C.a port being assigned as an alternate port
D.a root port being transitioned to the forwarding state

A.root port，designated port，alternate port，backup port，and disabled
B.standby port，alternate port，root port，and disabled
C.standby port，designated port，backup port，and disabled
D.root port，designated port，alternate port，and standby port

A.root port
B.backup port
C.designated port
D.alternate port

A.For each such address and mask /32, one label binding is created.
B.As the TCP endpoint, IP addresses are used by the LDP session.
C.These addresses are used to find the label binding to put in the LFIB, by looking up these IP addresses in the routing table.
D.These addresses are used for penultimate hop popping (PHP) when forwarding packets to the next router directly.