TCP vs UDP

TCP: Transmission Control Protocol

synchronous

1) Connection Oriented, 

2) Gaurantees the data transfer through 3 way communication

SYN, SYN-ACK, ACK

2) controls the order of the messags.

UDP:  User Datagram Protocol

Fire and Forget

1) Connection less

2) doesn't gaurantee the data transfer

3) ordering.

UDP: Anything where you don't care too much if you get all data always

• voice, video,
• streaming

TCP: Almost anything where you have to get all transmitted data

• Web
• SSH, FTP, telnet
• SMTP, sending mail
• IMAP/POP, receiving mail

Ip4 vs ip6

ip4

0 to 255  or 2^8.

computers understand binary format only. 0100010010, 010, 001 etc.

ip6:

next generatoin of ip address as we are running out of the ip's.

DHCP server: Dynamic Host Configuration Protocol server

dynamically allows Ip address to computers from the pool of available ip's addrsses from the subnet.lp

DNS: Domain Name Server, developed by network engineers.

Computers have ips address, humans understands domain names

Resolves names to numbers

amazon.com to 10,11,11,2

computers webbrowser----> OS cache can't find----->ISP------->Root Server directs to TLD(Top level domain server, .com/.net/.org)--->authoritative name server for ip address

Unix Commands:

uname -a to find the which kernel os is running

ifconfig to find the system ip address

df -ah to find out the free disk space

service servicename status

service servicename start

systemctl status servicename

du -sh foldername to check how much memory a folder is using

netstat -tdlpn  to check the open ports.

sudo gives access to root, there are some services we can run using sudo

sudo netstat -tulpn