Week 11: Layer 3 Primer Flashcards
What is the Address Resolution Protocol (ARP) used for?
Matching of network layer MAC Address to a link layer IP address. ARP is used to convert the IP Address into physical layer MAC Address
Explain how you would find out where a PC is located on a network using ARP?
a. Ping the IP address to generate an ARP request / reply
b. Follow the MAC Address to determine which switch the host resides on. Use show mac address-table to locate the switch port
What is HSRP - Hot Standby Router Protocol?
a. Cisco Proprietary
b. Provides fault tolerance for the default gateway
c. Provides a virtual MAC address and an IP address that is shared among a group of configured routers
What is a key difference between HSRP and GLBP?
a. HSRP provide for redundant routing
b. GLBP is Cisco Proprietary. Works the same as HSRP but provides for load balancing
What is enhanced object tracking and what is it used for?
if a link fails, the L3 device will subtract from its priority number and allow the standby device to take over. It must be accompanied by the preempt command on the other L3 device.
a. Allows HSRP to monitor a link and change its priority value if a link that is being tracked were to fail.
b. Causes for seamless failover to standby router based on the rules applied
c. Used when you have more than one downstream link
What are Maximum Transmission Units MTUs and why are they important?
a. Establishes the largest size that a data packet can be to traverse the wire. If the packet is too big it must be fragmented.
b. The default value for layer 2 networks is 1500 bytes
c. What is the MTU range for a Jumbo Frame
i. 1500-9000 bytes
d. MTU should always be set to the minimum MTU downstream from the source/sender perspective.
