When querying subnets via the API, only querying by ID works, not querying by name. Example:

curl -s -k -u admin:changeme https://r6-staypuft/api/subnets | python -m json.tool
[
    {
        "subnet": {
            "dhcp_id": 1, 
            "dns_id": 1, 
            "dns_primary": "192.168.130.5", 
            "dns_secondary": null, 
            "domain_ids": [
                1
            ], 
            "from": "192.168.130.100", 
            "gateway": "192.168.130.1", 
            "id": 1, 
            "ipam": "DHCP", 
            "mask": "255.255.255.0", 
            "name": "default", 
            "network": "192.168.130.0", 
            "priority": null, 
            "tftp_id": 1, 
            "to": "192.168.130.254", 
            "vlanid": null
        }
    }
]

[root@r6-staypuft ~]# curl -s -k -u admin:changeme https://r6-staypuft/api/subnets/1 | python -m json.tool
{
    "subnet": {
        "cidr": 24, 
        "dhcp": {
            "id": 1, 
            "name": "r6-staypuft.example.org", 
            "url": "https://r6-staypuft.example.org:8443" 
        }, 
        "dhcp_id": 1, 
        "dns": {
            "id": 1, 
            "name": "r6-staypuft.example.org", 
            "url": "https://r6-staypuft.example.org:8443" 
        }, 
        "dns_id": 1, 
        "dns_primary": "192.168.130.5", 
        "dns_secondary": null, 
        "domain_ids": [
            1
        ], 
        "from": "192.168.130.100", 
        "gateway": "192.168.130.1", 
        "id": 1, 
        "ipam": "DHCP", 
        "mask": "255.255.255.0", 
        "name": "default", 
        "network": "192.168.130.0", 
        "priority": null, 
        "tftp": {
            "id": 1, 
            "name": "r6-staypuft.example.org", 
            "url": "https://r6-staypuft.example.org:8443" 
        }, 
        "tftp_id": 1, 
        "to": "192.168.130.254", 
        "vlanid": null
    }
}

[root@r6-staypuft ~]# curl -s -k -u admin:changeme https://r6-staypuft/api/subnets/default | python -m json.tool
{
    "message": "Resource subnet not found by id 'default'" 
}