Networking Basics
What is Networking?
A network refers to two or more connected computers that can share resources such as data, a printer, an Internet connection, applications, or a combination of these resources.
Types of Network:-
1. LAN (Local Area Network):- Mostly covers buildings or a set of closely related buildings
2. MAN (Metropolitan Area Network):- Covers a metropolitan area or a small geographic area such as a small town.
3. WAN (Wide Area Network):- Covers countries, or a large geographic area.
Open System:- A system that is connected to internet and ready to communicate is called open system
Closed System:- A system is not connected to the internet and can’t be communicated with.
Network topologies:- The arrangement of devices connected to a network.
Some examples are:- Star, bus, Delta, ring, mesh, point to point, daisy chain, tree, hybrid etc.
Network Components:- A network connection may have multiple other devices by which communication also occurs. Eg:- Router, switch, hub, bridge, wireless router, etc.
Unique identifiers of a network:-
Each device in a network is associated with some unique identifiers by using which a device can be identified.
1. Host Name:- Each device in the network is associated with a unique device name known as Hostname which you can get t know by typing “hostname” in the command prompt (without quotation)
2. IP Address:- It is the logical address of a device connected to a network. It is a unique number assigned to every device connected to the internet. It has 2 versions IPv4 (32 bit long) and IPv6 (128 bit long). You can see it by typing “iconfig” in the command prompt for windows and “ifconfig” in Linux (without quote)
3. MAC Address:- This is the physical address. It is the unique identifier attached with each device NIC card (network interface card). It is 48 bit long. You can check it by using the same command “ipconfig/all”
4. Port:- Can be referred to as a logical channel using which data packets are transferred to any applications. It is a 16-bit long integer number and we have 216 ports available. Start from 0-65535 total 65536 ports. You can check by typing “netstat -a” by typing in the command prompt which ports are currently being used.
List of some important ports:-
20 FTP
21 FTP
22 SSH
23 Telnet
25 SMTP
53 DNS
69 TFTP
80 HTTP
88 Kerberos
110 POP3
123 NTP
135 Microsoft's RPC
137-139 Microsoft's NetBIOS
143 IMAP
161 SNMP
389 LDAP
443 HTTPS or HTTP over SSL
445 SMB
500 IKE
514 syslog
3389 RDP
5. Socket:- Combination of port and IP address is called socket.
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