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STANDARD streams are basically I/O (Input and OUTPUT) COMMUNICATION channels between a program and its environment in Linux. Input and output in the Linux environment are distributed ACROSS three standard streams. Three standard streams in Linux are as follows:

1. Standard Input (stdin)
2. Standard Output (stdout)
3. Standard Error (STDERR)

Hard Links: It is a special kind of file that points to the same underlying inode as another file. It can be referred to as an ADDITIONAL name for an existing file on Linux OS. Total number of hard links for a file can be displayed using the “ls -l” command. Such links cannot be used across file systems. Hard links can be CREATED using the following command: 
$ ln [original filename] [link name] 

Soft Links: It is also TERMED a symbolic Link. Soft links are kinds of FILES that usually point to another file. It does not include any amount of data in the target file and simply points to another entry anywhere in the file system. Such links can be used across file systems. Soft links can be created using the following command: 
$ ln -s [original filename] [link name] 

SSH (Secure Shell), as the name SUGGESTS, is BASICALLY a protocol that is being used to securely connect to remote servers or systems and enables two systems to COMMUNICATE. It is considered the most common way to have access to remote Linux servers. It generally transmits data over encrypted CHANNELS therefore security is considered at a high level. To connect to a remote server via SSH, you need to own a domain name and IP ADDRESS.

Default PORTS used for various SERVICES are as follows:

Different network bonding MODES used in Linux are listed below: 

• Mode-0 (balance-rr): It is the default mode and is based on round-robin policy. It offers FEATURES like fault tolerance and LOAD balancing. 
• Mode-1 (active-backup): It is based on an active-backup policy. In this, only one node RESPONDS or works at the time of failure of other nodes. 
• Mode-2 (balance-xor): It sets an XOR (exclusive-or) mode for PROVIDING load balancing and fault tolerance.  
• Mode-3 (broadcast): It is based on broadcast policy. It sets a broadcast mode for providing fault tolerance and can be used only for specific purposes.  
• Mode-4 (802.3ad): It is based on IEEE 802.3ad standard also known as Dynamic Link Aggregation mode. It sets an IEEE 802.3ad dynamic link aggregation mode and creates aggregation groups that share the same speed and duplex settings. 
• Mode-5 (balance-tlb): It is also known as Adaptive TLB (Transmit Load Balancing). It sets TLB mode for fault tolerance and load balancing. In this mode, traffic will be loaded based on each slave of the network.  
• Mode-6 (balance-alb): It is also known as Adaptive Load Balancing. It sets ALB mode for fault tolerance and load balancing. It doesn’t need any special switch support.  

Network Bonding, also known as NIC Teaming, is a TYPE of bonding that is USED to connect multiple network interfaces into a SINGLE interface. It usually improves PERFORMANCE and redundancy simply by increasing network throughput and bandwidth.

NIC (Network INTERFACE Card) teaming has several ADVANTAGES as given below: 

• Load Balancing  
• Failover  
• Increases UPTIME

/etc/resolv.conf: It is used to configure DNS name servers as it contains the DETAILS of the nameserver i.e., details of your DNS server. The DNS server is then used to resolve the hostname of the IP ADDRESS. 

/etc/hosts: It is used to map or translate any hostname or DOMAIN name to its relevant IP address.