Load Balancer Interview Questions & Answers part 1


Q: – What is Server Load Balancing?

Server Load Balancing (SLB) provides network performance and content delivery by implementing a series of algorithms and priorities to respond to the specific requests made to the network. In simple terms, SLB distributes clients to a group of servers and ensures that clients are not sent to failed servers.

Q: – What information needs to be provided in order to set up my appliance to do cookie load balancing?

You need the cookie name, cookie values, the VIP to bind to, and the groups to balance to.

Q: – What is Health Check in refer to load balancer ?

The Health Check feature of the load balancer that allows you to set parameters to perform diagnostic observations on the performance of web servers and web server farms associated with each appliance. Health checking allows you to determine if a particular server or service is running or has failed. When a service fails health checks, the SLB algorithm will stop sending clients to that server until the service passes health checks again.

Q: – When load balancing to a real server, which server will be accessed first?

This depends on the load balancing method that you select. Here are a few examples:

Least connections (lc) method " The real server with the lowest number of concurrent connections will receive the first connection. Round robin (rr) method " The real server with the lowest entry index will get the first connection. Shortest response (sr) " The loadbalancer or appliance will establish connections with each server and calculate the round trip time. The client connection will go to the real server with the lowest response time.

Q: -What is the difference between a Persistent Cookie policy and a QoS Cookie policy in array network loadbalancer ?

A Persistent Cookie policy selects a group based on the cookie name. A QoS Cookie policy selects a server group based on the cookie name and value assigned to that group.

Q: -What is Global Server Load Balancing (GSLB)?

GSLB operates very similarly to SLB, but on a global scale. It allows you to load balance VIPs from different geographical locations as a single entity. This provides geographical site fault tolerance and scalability.

Q: – Does Clustering need to be turned on in order to use GSLB?

Yes, Clustering must be configured and turned on in order to use GSLB. Each proxy within the site (or cluster) must have the same configuration. Hence, each appliance can act as a DNS server if it becomes a master for the site. Each site will have a unique cluster/SLB/GSLB configuration, and you will use the gslb site overflow command to add the remote GSLB site to the local appliance.

Q: – What load balancing methods are supported with array network GSLB ?

The Array appliance supports the following methods for GSLB:

1. lc " Least connections sends clients to the site that has the least number of current connections.
2. rr " Round robin simply sends client to each site in round robin succession.
3. overflow " Overflow allows requests to be sent to another (remote) site when the local site is 80% loaded.

Q: – What is Reverse Proxy Cache?

Reverse Proxy Cache is a cache that is in front of the origin servers, hence the use of the term reverse in the name. If a client requests a cached object, the proxy will service the request from the cache instead of the origin server.

Submitted By:-Nitu Chabra            Email-ID: – nituchabra@mail.com