Selected Answer: B Cisco definition: Unlike encapsulation, tunneling allows a lower-layer protocol and a same-layer protocol to be carried through the tunnel." Like stalkr3 said earlier: L2TP carries a lower-layer protocol (L2, like PPP). It is a tunneling protocol (hence the name) and not encapsulation. https://www.cisco.com/c/en/us/td/docs/ios/12_4/interface/configuration/guide/inb_tun.html#wp1045601

Selected Answer: D I think it's D, and here's why: Take a look at the L2TP header IN the IPSec packet in the diagram here: https://www.researchgate.net/figure/L2TP-over-IPsec-Encapsulation_fig10_330313436 It's not adding an extra header the way GRE does, as shown in the diagram here in fig 14.1: https://www.ciscopress.com/articles/article.asp?p=773666&seqNum=2 GRE adds its own required header to the IPSec packet and L2TP does not. Its header is encapsulated within the IPSec packet.

Selected Answer: D I think answer D is right, L2TP and GRE both encapsulate the packet of original header into another protocol, L2TP is an open standard and used for dial-up links to establish point-to-point tunnels but it does not encrypt traffic so IPSec is used to do that. However, GRE encapsulates the packet in IP and adds a new IP Header. GRE is a carrier protocol and IP is used for transport. GRE over IP is plain text tunnelling with IPSec providing encryption.

Selected Answer: A I believe A is correct. L2TP is actually a variation of an IP encapsulation protocol. GRE is a tunneling protocol which is used to transport multicast, broadcast and non-IP packets like IPX etc. IPSec is an encryption protocol.

Selected Answer: D https://ipwithease.com/gre-vs-l2tp/

If you read the question carefully, the answer is B

A is wrong. Per Cisco site:"Unlike encapsulation, tunneling allows a lower-layer protocol and a same-layer protocol to be carried through the tunnel." L2TP carries a lower-layer protocol (L2, like PPP). It is a tunneling protocol (hence the name) and not encapsulation.

Selected Answer: B GRE and IPSEC are two protocols

Selected Answer: D https://ipwithease.com/gre-vs-l2tp/

Selected Answer: A D is wrong, L2TP adds 8bytes of header ...Overhead is tallied for an IP header of 20 bytes, a UDP header of 8 bytes, and an L2TP header of 8 bytes.

A: is not correct since L2TP is frame encapsulation and gre over ipsec is not a single protocol. C: wrong D:L2TP also adds it own header So only B remains,its not clear for me but the other three answers seems wrong to me

i think B is write because GRE over ipsec is a combination of two protocols and cannot be used as standalone protocol, and L2TP can be used without security and encryption also we can use Ipsec to make it secure

Selected Answer: A https://www.ibm.com/docs/en/i/7.4?topic=concepts-layer-2-tunnel-protocol L2TP is actually a variation of an IP encapsulation protocol. The L2TP tunnel is created by encapsulating an L2TP frame inside a User Datagram Protocol (UDP) packet, which is then encapsulated inside an IP packet. https://learningnetwork.cisco.com/s/question/0D53i00000KstmKCAR/difference-between-gre-and-ipsec https://www.cloudflare.com/learning/network-layer/what-is-gre-tunneling/ GRE is a tunneling protocol

Selected Answer: B team B)

Selected Answer: B udp 1701 is used by the L2TP server, and L2TP adds it's own header, so we can rule out C and D. As I understand it, it uses udp for encapsulation, so A is not a good answer either. B) it can be used as a standalone. B is a strange answer, because it is very recommended to use L2TP together with IPsec. Still, I am going with B, because all the other answers seem to be wrong.

Yes B. C is obviously wrong. A is also wrong as L2TP is a tunnel protocol and what it encapsulates is the entire Ethernet frame, not just an IP packet, in addition, "GRE over IPsec" is not a protocol, it is using 2 protocols together. D is wrong too as L2TP does add its own header, just google for "L2TP header" and you will find the answer, the search result images are useful too.

Would have to vote B for this one as well... A is incorrect - L2TP IS a TUNNELING protocol. C is also incorrect - L2TP uses UDP and NOT TCP. D is also incorrect - L2TP includes an extra set of IP, UDP, and L2TP headers.

You can have gre tunnels protected with IPSEC, it is common if you want direct layer 3 connectivity, and run routing protocols between the GRE peers.

Answer b

Selected Answer: D these two protocols is that GRE over IPsec adds its own extra GRE header on top of the IPsec header, giving more flexibility for carrying multicast and routing protocol traffic