Networking contd

• Exercise: Create a network of size of approximately 160000 devices with 16 subnets of 8 thousand each

Network Size: 160000
2^n ~= 160000
n = 18
N = 32-18 = 14

network cidr: 172.16.0.0/14
network SM:   11111111.11111100.00000000.00000000

subnet size: 8000
2^n ~= 8000
n = 13
N = 32-13 = 19

network SM: 11111111.11111100.00000000.00000000
subnet  SM: 11111111.11111111.11100000.00000000
-----------------------------------------------
                 172.000100xx.xxx00000.0/19
                 172.00010000.00000000.0/19 => 172.16.0.0/19
                 172.00010000.00100000.0/19 => 172.16.32.0/19
                 172.00010000.01000000.0/19 => 172.16.64.0/19
                 172.00010000.01100000.0/19 => 172.16.96.0/19
                                            => 172.16.128.0/19
                                            => 172.16.160.0/19
                                            => 172.16.192.0/19
                                            => 172.16.224.0/19

• Exercise: Lets create a network of 400000 (4 lakh devices) with 16 subnets of approximately 25000 devices.

Network Size : 4 lakh

2^n ~= 4 lakh
n = 19
N = 32 - 19 = 13

Network cidr= 172.16.0.0/13
Subnet Mask = 11111111.11111000.00000000.00000000

Subnet Size :  25000
2^n ~= 25000
n = 15
N = 32-15 = 17

Network SM: 11111111.11111000.00000000.00000000
Subnet SM:  11111111.11111111.10000000.00000000
------------------------------------------------
                 172.00010xxx.x0000000.0/17
                 172.00010000.00000000.0/17 => 172.16.0.0/17
                 172.00010000.10000000.0/17 => 172.16.128.0/17
                 172.00010001.00000000.0/17 => 172.17.0.0/17
                 172.00010001.10000000.0/17 => 172.17.128.0/17
                                            => 172.18.0.0/17
                                            => 172.18.128.0/17
                                            => 172.19.0.0/17
                                            => 172.19.128.0/17
                                            => 172.20.0.0/17
                                            => 172.20.128.0/17
                                            => 172.21.0.0/17
                                            => 172.21.128.0/17
                                            => 172.22.0.0/17
                                            => 172.22.128.0/17
                                            => 172.23.0.0/17
                                            => 172.23.128.0/17

DHCP and DNS

• When we connect any device to a network it gets an ip which is issued by DHCP Server.
• IP Can be
  • Static
  • Dynamic
• DNS Server can resolve hostnames/domain names to ip addresses
  • Hostname/Domain name to IpAddress
  • Alias to Host/Domain
• DNS servers are two kinds
  • Public DNS Servers
  • Internal/Private DNS Servers.