Explain DNS Load Balancing in simple way!
The main concept behind DNS Load Balancing is to distribute the traffic to different servers with the assistance of DNS Servers. In this the DNS Query resolves to multiple IP Addresses in random order.
To Note, there are total of 13 Root Server IP’s in the world!
Why only 13 root servers?
The DNS Packet is 512 Bytes with each IP Address having 32 Bytes for 13 total data is 416 bytes.
96 bytes are left to be added for other data or IPs’ to be added in future.!
How would you check the connection between two machines?
telnet host port
How would you what all ports processes are running?
netstat — pln
How would you see the sorted files by time?
ls -ltr
What makes by adding TCP+IP making it a reliable protocol?
Internet Protocol is best effort delivery, it doesn’t ensure that the packet will reach. But by adding TCP with IP, it makes more reliable.
Some features like retransmission of packets when it is lost and in-order delivery of packets and acknowledgements makes TCP/IP more reliable.
Explain [!#/bin/bash]
It’s denoted as Shebang and it tells the interpreter path where the script is running.
How would you create a file and the recurring directory like /etc/test/innertest/file ?
I would go with this command mkdir-p.
pwd — (Command used to print working directory)
How would you check whether DNS is resolved or not?
By using the command dig or nslookup, with dig, you can look for the answer section, with nslookup command, you can check the address section.
How would you see the nameservers are used for DNS Resolution?
dig+trace is generally used to see the nameservers for DNS Resolution.
Systems Calls
fork() — Used for creating the process.
open() — System call used for opening the file in the process.
Why .bashrc() exaclty used?
When you open a terminal, some scripts are to be executed, those can be placed in .bashrc()
Explain Linux Aliases!
Alias is generally used to instruct the bash to replace a particular string with a predefined command.
It can be added in .bashrc or in .bash_profile something like this alias l = ‘ls’.
When l typed, the command gets executed.
What are the different system calls that gets executed?
fork(), exec(), wait(), exit()
How would you list all hidden files?
ls-a (to be written)
More Concepts to be covered in Part-2 of the Article.!
