简答题 BGP Administrative distance？

A.Attempt to TELNET from the router connected to the inside of the firewall to the router connected to the outside of the firewall.If telnet works，BGP will work，since telnet and BGP both use TCP to transport data
B.Ping from the router connected to the inside interface of the firewall to the router connected to the outside interface of the firewall.If you can ping between them，BGP should work，since BGP uses IP to transport packets
C.There is no way to make BGP work across a firewall without special configuration，so there is no simple test that will show you if BGP will work or not，other than trying to start the peering session
D.There is no way to make BGP work across a firewall

A.The TTL field from the IP packet is copied into the TTL field of the MPLS label header at the ingress edge LSR
B.TTL propagation cannot be disabled in an MPLS domain
C.TTL propagation is only disabled on the ingress edge LSR
D.The TTL field of the MPLS label header is set to 255
E.The TTL field of the IP packet is set to 0