Skip to main content

Network Addresses

IP addresses uniquely identify nodes across the internet. They are registered using an ISP.

There are two versions of IP address:

  • IPv4: 32-bit address composed of 4 octets, 148.114.252.10
  • IPv6: 128-bit address composed of 8 16-bit octet pairs, 2003:0db5:6123:0000:1f4f:0000:5529:fe23

IPv4 Address Types​

  • Unicast: An address associated with a specific host.
  • Network: An address whos host portion is set to all binary zeroes, e.g. 192.168.1.0.
  • Broadcast: An address to which each member of a particular network will listen. Will have the host portion set to all 1 bits, e.g. 172.16.255.255.
  • Multicast: An address to which appropriately configured nodes will listen, e.g. 224.0.0.2. Only nodes specifically configured to pay attention to a specific multicast address will interpret packets for that multicast group.

Reserved Address​

  • 127.x.x.x: loopback address.
  • 0.0.0.0: address when attempting to communicate with server.
  • 255.255.255.255: General broadcast private address.
  • 10.x.x.x, 172.16.y.y, 192.168.z.z.

IPv4 Address Classes​

v3

Netmasks are used to determine how much of the address is used for the network portion and host portion.

subnet

Managing Hostname​

The hostname is a label to identify a networked device. For DNS, hostnames are appended with periods to create the FQDN.

To set the hostname for the session only:

sudo hostname myhost

To modify the hostname permanently:

sudo hostnamectl set-hostname myhost

The value is stored in:

/etc/hostname