General questions
These questions help the interviewer understand your interest in the position and get to know you:
What do the terms Btu, CAV and AHU mean?
There are many acronyms used in the HVAC industry. Hiring managers want to know that youre familiar with basic HVAC terminology because youll need to thoroughly understand these terms and their uses for technical purposes. In addition, being able to explain the mechanical uses and benefits of HVAC equipment in easy-to-understand terms to your clients can make you a more approachable technician. When answering the question, keep your response on each term short and informative.
Example: “Btu stands for British thermal unit, which is how much energy you need to heat or cool one pound of water by 1 degree Fahrenheit. In an air conditioning unit, the Btu number given is the total amount of heat the AC unit can pull out from the air in one hour.
CAV stands for constant air volume. CAV measures the volume of air supply through the distribution system while heating or cooling the air in a room. An AHU is an air handling unit, which HVAC professionals install to circulate the air in an air conditioning system.”
In-depth questions
These specific questions help the interviewer understand how you work and how you handle problem-solving scenarios:
What is VRF?
VRF meaning is Virtual routing and Forwarding which is a technology that allows multiple instances of a routing table to co-exist within the same router at the same time.
Because the routing instances are independent, overlapping IP addresses can be used without conflicting with each other.
The multiple Routing instances can be made to traverse different path (ie take different outgoing interfaces).
VRFs are the same methods of network isolation/virtualization as VLANs.
Related – VLAN vs VRF
VLANs are used at the L2 and VRFs are L3 tools.VRFs are to routing table like VLANs are to LANs.
Using Virtual routing and forwarding we are virtualizing routing table into multiple routing tables, similarly to VLANs used to virtualize LANs.
One could say that VLANs are performing L2 virtualization, VRFs are performing L3 virtualization. VLANs make a single switch look like several switches; Virtual routing and forwarding make a single router look like several routers.
VRF Flavours –VRF and VRF Lite
VRF has earned so much popularity in recent years due to its versatility in Data Centers, Corporate LANs and most importantly in Service provider domain.
While we talk about Service providers running MPBGP in MPLS Cloud, VRF is one of the key ingredient responsible for routing multiple customer traffic across the same underlying infrastructure.
Using VRF in provider MPLS domain increases network security and also allows segregation of customer traffic over WAN even in scenarios of overlapping address space.
Considering the superb performance of VRF, its lighter version (VRF Lite) has been widely embraced in Data Center and Campus LAN environments.
Unlike full-blown VRF, VRF Lite does not require configuration of MPBGP including some parameters like Route target etc.
In fact, it is used in data centres to provide end to end segregation of traffic belonging to different zones likes DMZ, Extranet and Inside Zones.
Such an approach has drastically reduced physical infrastructure requirements by using different Logical Routing tables (thanks to VRF Lite).
It segregates traffic of various traffic zones without the need for dedicated physical devices to perform these tasks.
FAQ
How does the VRF system work?
What is difference between VRF and VRV?
What is the benefit of VRF?
