Troubleshooting Network Issues

Question 1

Broadcast Storm

Answer 1

Occurs when a network system is overwhelmed by continuous multicast or broadcast traffic

Question 2

What are the best ways to break up broadcast storms?

Answer 2

Enable Bridge Protocol Data Units (BPDU) on managed switches
Enforce a maximum number of MAC addresses per port
Break up large broadcast domains into smaller domains using routers and Layer 3 switches

Question 3

Logical Domain Manager

Answer 3

Listens to multicast messages on a network and keeps track of the MAC addresses being used

Question 4

What’s one way you can prevent duplicate MAC addresses on your computer?

Answer 4

Enable port security on your switches

Question 5

Duplicate IP Address/IP Address Conflict

Answer 5

Occurs when another computer on the same network has an identical IP to another workstation or server on the same network

Question 6

What are the usual reasons for duplicate IPs?

Answer 6

Static IP address issue
DHCP server issue
Rogue DHCP server

Question 7

Multicast Flooding

Answer 7

No specific host is associated with the multicast MAC address in the CAM table of the switch

Question 8

Asymmetrical Routing

Answer 8

Network packets leave via one path and return via a different path

Question 9

What will help you find a missing route?

Answer 9

show ip route

Question 10

Switching/Bridge Loop

Answer 10

Occurs whenever there is more than one path between the source and destination devices

Question 11

Routing Loop

Answer 11

Formed when an error occurs in the operation of the routing algorithm and creates a circular route amongst a group of network devices

Question 12

What are routing loops caused by?

Answer 12

logical layer 3 circular connectons that may exist in a routing table

Question 13

What can you do to prevent routing loops

Answer 13

make the TTL 0
Split Horizon

Question 14

What is split horizon?

Answer 14

Routing configuration that stops a route from being advertised back in the direction from which it came

Question 15

Route Poisoning

Answer 15

increasing a router’s metric to an infinitely high number after detecting one of its connected routes has failed

Question 16

Hold-Down Timer

Answer 16

Prevents bad routes from being restored and passed to other routers by accident

Question 17

How can you counteract a rogue DHCP server?

Answer 17

DHCP snooping, port security, intrusion detection

Question 18

DHCP scope exhaustion

Answer 18

this is when you run out of valid IPs to use

Question 19

What are some things you want to keep in mind with firewall issues?

Answer 19

Ensure there are no typos in your rules
Verify the protocol and port numbers references by the rule are correct
Verify the source and destination addresses are referenced by the rule
Verify the order of the rules is applied correctly

Question 20

Five main reasons for network performance issues?

Answer 20

High CPU usage
High bandwidth usage
poor connectivity
network malfunction
DNS problems

Question 21

Optical Link Budget

Answer 21

A calculation that considers all the anticipated losses along the length of a fiber optic connection