For First Question
HDLC and PPP are encapsulation "or a way" for Frame Relay to communicate like when you use ISL or Dot1q for trunking, to tell the truth this kind of question u will not understand it without hands on for frame relay on GNS3 to feel it, if u want videos for Frame Relay here u go
no need to see it all but just the first 4 or 5 videos are enough to have a good understand of the technology itself
it's a tricky question but easy if u know the mechanism of STP in general
to understand this question first u need three informations
1-the part u will apply on and here u will only work on the access switches so u will forget about switch 1 and 2 and play on switch 3 and 4
2- in Switching everything as long as it's lower it's the strongest, and in routing as long as it's higher it's the strongest
3-the election process and "mainly it depends on the following rules
I- Priority ID : an ID u set it up for the switch by different way either to put is or else by making a primary or secondary configuration "i think this is a CCNP" but as a general information
II- Mac Address : in details it's in sybex book and CCNA but in a general way it's a hard coded address and they are different from every device to another in the entire world and u can say it's like as we human have fingure prints the devices have mac address , in some devices there is more than one mac address simple example like the laptop "for ethernet" there is a mac and "For wireless" there is another mac...etc
III- port ID : the physical port in the switch "but in the election u may use the far side of ur port as Sheno and i was discussing and as usual he won the debate"
anyway to simplify this issue
if u have two switch connecting in a mesh way, means connecting with two lines as sw 3 and sw 4, we will use stp to avoid the collision as it will be like a circule and data will make this CSMA/Cd so stp rule is to block on port for others to survive. "on for all theory - king arthur"
so how can we make this election
if u just connected two switch without any further configuration the blocked port will be in the one who have the highest mac address "BUT" if you have configured priority ID then the switch with highest ID will have the blocked port
but in case we have both with the same priority we will go to the next step which is the Mac address "they are unique no one can make them identical"
in this case we have two lines connected but after the priority ID are Identical and the mac address of Sw 3 is lower than Sw 3 then Sw4 is the one that will be holding the blocked port
then jumping to the third way, the lowest port is the strongest and the highest will die "switching rule"
so here we have port fa 0/2 and fa0/11, the lowest survive and the higher will die for others to live
here fa0/11 will be the blocking because it's the highest port in the highest mac address switch so it will be the blocking, there is another theory that if u cahnged the link from fa0.1 to fa0/11 and from fa0/12 to fa0/2 the blocking one will be fa0/2 because it's counted from the far end switch, or the stronger switch that have either a lower Priority ID or Mac Address or Port ID,
so if we changed fa 0/1 to Fa0/11 and fa0/12 to fa0/2 then the blocked port will be fa0/2 on sw 4 because in the strong switch which is SW the highest port id "fa0/12" which make it the weakest, far end of it will be the blocking, but fa0/1 the lowest Id "the strongest" far end is the strongest as it's root is stronger than the root of f0/12
For 3 and 4 i remember that i memorized them just like that at the time of CCNA exam
hope u get the info and if u need further information contact me at my skype ah.bakir