Many home networks default to 192.168.1.x/24 because it's the simplest configuration for consumer-grade routers. However, in enterprise environments like universities and corporate networks, you'll frequently encounter 172.x.x.x addressing. This isn't accidental - it's a deliberate design choice with technical and organizational benefits.

The Internet Assigned Numbers Authority (IANA) reserved three blocks of IPv4 addresses for private networks:

10.0.0.0/8 (10.0.0.0 - 10.255.255.255)
172.16.0.0/12 (172.16.0.0 - 172.31.255.255)
192.168.0.0/16 (192.168.0.0 - 192.168.255.255)

1. Network Segmentation Flexibility
The 172.16.0.0/12 range provides 16 contiguous class B networks (172.16-172.31), allowing for better organizational structure:

172.16.0.0/16 - Campus Building A
172.17.0.0/16 - Building B
172.18.0.0/16 - Wireless Network
...
172.31.0.0/16 - DMZ

2. Avoidance of Common Conflicts
Many consumer devices default to 192.168.0.0/24 or 192.168.1.0/24. Using 172.x.x.x reduces collision risks when remote workers connect VPNs.

3. Future-Proof Scaling
A /12 prefix provides 1,048,576 addresses versus 192.168's 65,536 (/16). This accommodates large-scale networks without NAT overloading.

Here's how a university might configure their DHCP server:

# Example ISC DHCP configuration for 172.16.0.0/16
subnet 172.16.0.0 netmask 255.255.0.0 {
    option routers 172.16.0.1;
    option domain-name-servers 8.8.8.8, 8.8.4.4;
    range 172.16.10.1 172.16.254.254;
    default-lease-time 86400;
    max-lease-time 172800;
}

Use 192.168.x.x when:
- Deploying small office/home office networks
- Needing simple configurations
- Working with consumer-grade equipment

Opt for 172.x.x.x when:
- Managing large-scale networks
- Requiring hierarchical network design
- Anticipating VPN connectivity needs
- Planning for future growth

Enterprise networks often implement route summarization with 172.x.x.x:

# Cisco IOS example
router ospf 1
 network 172.16.0.0 0.15.255.255 area 0

This single line advertises all 16 networks from 172.16-172.31, significantly reducing routing table size.

The 172.x.x.x range offers psychological security benefits - potential attackers scanning networks often prioritize 192.168.x.x subnets first. While this shouldn't be primary security, it provides a minor deterrent.

For organizations transitioning from 192.168 to 172 addressing:

#!/bin/bash
# Sample re-ip script (simplified)
OLD_SUBNET="192.168.1"
NEW_SUBNET="172.16.10"

for host in {1..254}; do
    ssh admin@${OLD_SUBNET}.${host} "sed -i 's/${OLD_SUBNET}/${NEW_SUBNET}/g' /etc/network/interfaces"
    ssh admin@${OLD_SUBNET}.${host} "reboot"
done

RFC 1918 defines three blocks of private IPv4 address space:

10.0.0.0/8 (10.0.0.0 - 10.255.255.255)
172.16.0.0/12 (172.16.0.0 - 172.31.255.255)
192.168.0.0/16 (192.168.0.0 - 192.168.255.255)

University networks and corporate environments often choose 172.x.x.x for these technical reasons:

• Scalability: The 172.16.0.0/12 range provides 1,048,576 addresses (16 contiguous /16s) compared to 192.168.0.0/16's 65,536
• Segmentation flexibility: Easier to create hierarchical network designs using the mid-range /12 mask
• VPN compatibility: Less likely to overlap with home networks using 192.168.x.x

Here's how network admins typically configure subnets:

// Campus network segmentation example
172.16.0.0/16 - Administration
172.17.0.0/16 - Faculty
172.18.0.0/16 - Student Housing
172.19.0.0/16 - Research Labs

Sample ISC DHCP server configuration for 172.x.x.x:

subnet 172.20.0.0 netmask 255.255.0.0 {
  range 172.20.10.1 172.20.20.254;
  option routers 172.20.0.1;
  option domain-name-servers 8.8.8.8, 8.8.4.4;
}

Small networks benefit from 192.168.x.x because:

• Simpler to remember and document
• Default for most consumer routers
• Sufficient for networks under 254 devices

The 172.16.0.0/12 range allows more flexible subnetting:

// Network calculator output for 172.16.0.0/12
Network:   172.16.0.0/12
HostMin:   172.16.0.1
HostMax:   172.31.255.254
Hosts/Net: 1,048,574
Subnets:   16 (as /16s)