Cloud

Question 1

What is KVM?

Answer 1

Kernel-Based Virtual Machine - Module lets Linux function as a hypervisor.

Question 2

HOW does a network switch function?

Answer 2

How: Layer 2 uses MAC addresses to send packet to right place.

Question 3

WHAT is a network switch?

Answer 3

Device for connecting devices together in a network.

Question 4

What is a router? How does it function?

Answer 4

Device for forwarding packets at Layer 3 between networks.

How: Reads network packet header and uses routing table to forward the packet.

Question 5

What is DHCP? Why?

Answer 5

Dynamic Host Configuration Protocol. Allows clients to retrieve and be dynamically assigned IP address.
Why: Automated, centralized, reuse/allocate IPs.

Question 6

What is Address Resolution Protocol?

Answer 6

Layer 2 Protocol for a computer to retrieve a physical MAC address of another computer from using a IP address.

Question 7

What is a VLAN?

Answer 7

Broadcast domain partitioned at Layer 2 (Data link layer). Used to logically segment networks independent of physical structure (ex: company departments).

Question 8

What is vCenter?

Answer 8

Centralized management utility for VMware, and is used to manage virtual machines, multiple ESXi hosts

Question 9

What is vMotion?

Answer 9

VMWare technology that allows live migration of a VM to be moved from one physical host server to another, while it is running and with no interruption in service.

Question 10

What is ESXi?

Answer 10

VMWare enterprise-class, type-1 hypervisor

Question 11

Hypervisor

Answer 11

What is is computer software, firmware or hardware that creates and runs virtual machines by running on a host machine and creates guest VMs?

Question 12

What is the 2nd layer in OSI model?

Answer 12

Data link layer

Question 13

WHY does data link layer exist?

Answer 13

Move packets between two nodes intra-network using framing, physical addressing.

Question 14

HOW does data link layer work? (2 protocols, 2 explicit)

Answer 14

Medium access control (MAC) and logical link control (LLC).

ex: 802.3 Ethernet, 802.11 Wi-Fi

Question 15

What is Layer 2 traffic which the sender does not know the network address. Broadcast, unknown-unicast, multicast.

Answer 15

BUM traffic

Question 16

HOW does Address Resolution Protocol work? (3 steps)

Answer 16

Computer first checks ARP cache
If not found, send ARP broadcast on network requesting MAC for IP.
Dest computer answers.

Question 17

WHAT is the 3rd layer in OSI model?

Answer 17

Network Layer

Question 18

WHY does 3rd layer in OSI model?

Answer 18

Why: Break segments into packets, move between inter-networks to right place.

Question 19

HOW does 3rd layer in OSI model work?

Answer 19

How: Routing and addressing (IP)

Question 20

WHAT is the 4th layer in OSI model?

Answer 20

Transport Layer

Question 21

WHY does 4th layer in OSI model?

Answer 21

Why: Breaks message data into segments for flow control & error control.

Question 22

HOW does 4th layer in OSI model work?

Answer 22

How: TCP, UDP, and Ports.

Question 23

What is Open vSwitch?

Answer 23

Open source distributed virtual multilayer switch

Question 24

What is OpenFlow?

Answer 24

Communication protocol that allows remote administration of a layer 3 switch’s packet forwarding tables, by adding, modifying and removing packet matching rules and actions.

Question 25

What is multiplexing?

Answer 25

Combining multiple signals over a shared medium

Question 26

What is a port? WHY is port useful?

Answer 26

Numbered network endpoint for OS to identify a process/service. Allows computer to multiplex incoming data to specific process/service.

Question 27

What is ICMP?

Answer 27

(Internet Control Message Protocol) L3 protocol to send messages indicating success or failure when communicating with another IP address

Question 28

What is IPSec? What are its constituent protocols?

Answer 28

L3 Network protocol suite that authenticates and encrypts the packets of data to provide secure encrypted communication between two computers. (Authentication Header, Encapsulating Security Payloads, ISAKMP/Security Associations)

Question 29

What port does IPSec use?

Answer 29

Port 500

Question 30

What is Authentication Header (AH)?

Answer 30

L3 IPSec Protocol with a header that provides authentication and integrity (but not encryption). It uses a Integrity Check Value (ICV) hash.

Question 31

What is Encapsulating Security Payload?

Answer 31

L3 IPSec Protocol with header and trailer that encrypts data in transport-mode, or encrypts data+ip header in tunnel-mode.

Question 32

What is Security Association (SA) and what's are 4 things it's composed of?

Answer 32

L3 IPSec protocol(s) for authenticated simplex data connection between two endpoints. It's an agreement on encryption algo (SHA/DES), key material, endpoint IPs, IPSec protocol (AH/ESP).

Question 33

What is VXLAN?

Answer 33

Protocol encapsulates Layer 2 Ethernet frames in Layer 3/4 UDP packets, enables you to create virtualized Layer 2 subnets, or segments, that span physical Layer 3 networks.

Question 34

Which IP blocks are for private/local networks?

Answer 34

10.x.x.x, 176.(16-31).x.x, 192.168.x.x

Question 35

What is STT?

Answer 35

Stateless Transport Tunneling protocol for virtual network running on top of a physical network. Alternative to VxLAN.

Question 36

What is VRRP?

Answer 36

Virtual Routing Redundancy Protocol: provides automatic assignment of available IP routers to hosts. Primary virtual router sends advertisements. If a backup device does not receive an advertisement for a set period, the backup device with the next highest priority (1 to 255) takes over as primary and begins forwarding packets.