What are Inferior and Superior BPDUs of STP

Today i want to have a very brief talk about what the Spanning-Tree Inferior and Superior BPDUs are and what is the difference between them.

Inferior BPDU of STP
The BPDU is considered inferior, if it carries information about the root bridge that is worse than the one currently stored for the port, or the BPDU has longer distance to reach the current root bridge. Inferior

gns3 Configurations are deleted/are not saved when restarted

Probably you are using gns3 for the fist time and getting this problem! that when you make you topology, make all configurations, save it and when you restart the gns3 all the configurations are gone away, and only the topology diagram is there?

Don't worry it is because you are missing one step while saving your Router's configurations in gns3, that is you have to export the configurations after that you have to save the gns3 file. 

How to configure EIGRP to work with Discontiguous Networks

EIGRP is a classless Routing Protocol, but like RIP and RIPv2 it auto summarizes subnets to their classfull boundaries. So in the environment where you have Discontiguous Networks, EIGRP is not going to work until you prevent EIGRP manually from Auto Summarization.

RTP, Reliable Transport Protocol of EIGRP

RTP is a Cisco proprietry protocol, used in EIGRP to manage the communication of messages between EIGRP-Speaking Routers.

Reliable Transport or Delivery of EIGRP packets means Acknowledgement is required from the receiving Router and the packet should be delivered in order. Ordered delivery is ensured by including two sequence numbers in the packet. One sequence Number is assigned by the sending router for the packet order Number and that is incremented by one each time the sending Router sends a packet. Another Number is the Last Acknowledgement number received from destination or Neighbor Router.

Why MAC address is used and not only IP Address for Networking

Though A very basic Question but asked by CCNA Beginners!

MAC address(Identifier) or Hardware Address that is burnt on the Network Interface Cards by its manufacturing companies is used for communication because devices on a LAN must also be uniquely and individually identified or they, like humans sharing the same name, will receive data not intended for them.