most favorite interview questions by recruiters...(3)

Que-1 Explain TCP handshake.
Answer: syn
syn-ack
ack

Que-2 How does spanning tree prevent loops?
Answer: By selecting a root bridge ( lowest priority)
Determine the least cost paths to the root bridge on each segement - designated ports
Disable all other root paths.

Que-3 What are the 5 port states?
?Port States
Legacy ST Rapid ST
Answer: Disabled
Blocking Discarding
Listening
Learning Learning
Forwarding Forwarding

Que-4 Name most usable BGP attributes.
Answer: Weight
Local preference
Multi-exit discriminator
Origin
AS_path
Next hop
Community

Que-5 What is IGMP snooping used for?
Answer: To cut down on switch resources. It checks each multicast packet for joins/leaves

Que-6 How is a mulitcast designated router elected?
Answer: Highest IP address


Que-7 You have area 0 and area 1, what is the router in between these two area's called?
Answer: ABR

Que-8 how to create end-to-end MPLS VPNs using multiple carrier MPLS networks. LOL I nearly died.
Answer: MPLS-ICI device much like a FR NNI interface. And then import/export the route targets that correspond to the particular VPN.

Que-9 Name some issues with QoS when traversing multiple ISP networks?
Answer: One ISP might use DSCP, one might use IP Precedence and the third might use DSCP also, hence there needs to be an agreement end-to-end for proper QoS propagation

Que-10 When tracking an interface using HSRP (or another protocol) how would you know that a Metro Ethernet link is down?
Answer: In metro ethernet we usually see the link as UP/UP, even though the CE router has lost connection to the aggregation switch, because of this we cannot take the interface protocol as our main way of telling connectivity. We can use ICMP and IP SLA to track an object in this case. Or else some way check the protocol status such as BGP (as this will be in active)