Computer Networking

 Domain Name Service/System Has a table that maps IP addresses to the domain names All nodes on a network need to be aware of the DNS ip-address so that they can send the requests with domain-names to the DNS and then DNS can forward the request to respective destinations.

DHCP : Dynamic Host Configuration Protocol Network management protocal Assigns IP addresses, dynamically, to all the devices connected in a LAN  DHCP server also has an IP address because it is a device Here is an example of DHCP configuration To implement the DHCP service, we need the DHCP server

Components of a Computer Network Nodes End Nodes (Senders and Receivers) Intermediate Nodes e.g.  Hub Physical layer One-to-all (broadcasts), it is not one-to-to(unicast) Can't store or keep track of MAC addresses so can't unicast so may lead to unnecessary traffic in the network, not efficient! Receives data packets from one port and broadcasts it to all other ports e.g. a hub can have 8 or 4 or any number of ports and all these ports are connected to individual nodes(devices) Can be used to create LANs Repeater Physical layer Used to regenerate the signal over the same network before it becomes too weak They do not amplify but increase the intensity of the signal e.g. optic fibers can only be effective for sending signals without becoming weak for up to 60 km or so Also do not concern themselves with the MAC addresses for the machine Bridge Data-link layer Connects two LANs : One port - One LAN Uses MAC addresses to forward the data MAC addr. PC1 -> Port 1 MAC addr. PC1 -...

 

 Firewall is a security mechanism for networking traffic.

Gateways and Route Tables enable inter-network communications. There can be multiple gateways in a network which connect the network to different other networks, so a packet originating from inside this network needs to know which gateway to take up to reach its destination and Route Tables help the packet find the right gateway.

Dynamic Host Configuration Protocol Two questions: When we add a computer to a network, what is the IP address it is going to get? What is the DNS server in the network? We can either manually assign IP addresses to these computers and then manually configure the DNS for it OR  We can automate it and that is where DHCP comes into play, it automatically assigns an IP address to the computer that has been newly added to the network and manages the DNS related options for it.

Internet is a Public network,  So that IP addresses in private networks do not clash with IP addresses on the internet(public network), some particular IP range are reserved for the purpose of private networking Reserved IP ranges(CIDR) for private networking and this CIDR is never given to computers on the public internet 10.0.0.0/8 172.16.0.0/12 192.168.0.0/16 Obviously multiple private networks can have the same CIDR but you can not interconnect two private networks having the same CIDR

CIDR, or Classless Inter-Domain Routing, is a method for allocating and specifying IP addresses in a flexible and scalable way. When you define a PRIVATE network, you specify what is its CIDR by means of which you identify the entire IP addressing scheme for the network and you get to know what is the range of IP addresses for the network. By doing so I can size the network CIDR : Classless Inter Domain Routing IP addresses are assigned to devices based on a CIDR Specifies the range of IP addresses for the network e.g. 10.0.0.0/16 or 192.168.0.0/16 If we assign 10.0.0.0/16 as the CIDR for a network, then it means the first 16 bits are fixed i.e. the IP address range for the network would be from 10.0 .0.0 - 10.0 .255.255 If I assign 192.168.1.0/24 as the CIDR then I am reserving the first 24 bits for this network and those 24 bits are fixed, which means that the entire network shall have IP addresses in the range 192.168.1 .0 - 192.168.1 .255 The fixed part is called the Network Prefi...

 DNS : Domain Name Server A server that keeps the mapping of Hostnames and IP addresses Resolves Hostname to IP addresses It has it's own IP address IP Addressing IPv4 32 Bit --------.--------.--------.-------- (2^32)  IPv6 128 Bit (2^128)

Components of a Computer Network DHCP service DNS service IP Addressing IP Address range and Network CIDR e.g. 10.0.0.0/16 Private and Public Networks Subnets, NICs and Bonding DHCP in Networking Gateways and Route Tables Network Firewall Private Connectivity in Networking