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VLANs, Subnets, and Broadcast Domains
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VLANs, Subnets, and Broadcast Domains

MediumSQL · PostgreSQL

Problem

Explain how VLANs and subnets differ, what broadcast domains are, and when you would use each.

Using the provided network inventory tables, write a query that reports the relationship between VLANs, subnets, broadcast domains, and active devices. Include records that lack a matching VLAN, subnet, or device.

Output

  1. One row per VLAN-subnet or unmatched network record, with vlan_id, vlan_name, cidr, broadcast_domain_id, network_design_note, and active_device_count.
  2. Sort by vlan_id ascending, then cidr ascending, with unmatched values last.

Schema

vlans
ColumnTypeDescription
vlan_idPKINTVLAN identifier
vlan_nameVARCHAR(100)Human-readable VLAN name
siteVARCHAR(100)Physical site
broadcast_domain_idINTIdentifier for the Layer 2 broadcast domain
purposeVARCHAR(100)Intended network use
subnets
ColumnTypeDescription
subnet_idPKINTSubnet identifier
vlan_idINTAssociated VLAN identifier
cidrVARCHAR(30)CIDR network range
network_roleVARCHAR(100)Intended Layer 3 network role
network_devices
ColumnTypeDescription
device_idPKINTDevice identifier
device_nameVARCHAR(100)Device name
vlan_idINTConfigured VLAN identifier
device_typeVARCHAR(50)Device category
is_activeBOOLEANWhether the device is currently active
Tablesvlanssubnetsnetwork_devices
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