DNSMASQ Libvirt

Hi, Net-dump xml File. root@NFV-FRU:~# virsh net-dumpxml data-2 <network> <name>data-2</name> <uuid>ace4935f-0367-4632-be7c-61bab2da7d4a</uuid> <bridge name='data-2br1' stp='on' delay='0'/> <mac address='52:54:00:46:43:7d'/> <ip address='10.12.12.1' netmask='255.255.255.240'> <dhcp> <range start='10.12.12.4' end='10.12.12.4'/> </dhcp> </ip> </network> The DHCP response is going with Subnet Mask 255.255.255.0 10.12.12.1.bootps > 10.12.12.4.bootpc: [udp sum ok] BOOTP/DHCP, Reply, length 300, xid 0x7331d77a, Flags [none] (0x0000) Your-IP 10.12.12.4 Server-IP 10.12.12.1 Client-Ethernet-Address 52:54:00:5f:ab:94 (oui Unknown) Vendor-rfc1048 Extensions Magic Cookie 0x63825363 DHCP-Message Option 53, length 1: Offer Server-ID Option 54, length 4: 10.12.12.1 Lease-Time Option 51, length 4: 3600 RN Option 58, length 4: 1800 RB Option 59, length 4: 3150 Subnet-Mask Option 1, length 4: 255.255.255.0 BR Option 28, length 4: 10.12.12.255 Domain-Name-Server Option 6, length 4: 10.12.12.1 Can I know the reason ? Thanks & Regards Santhosh Kumar Gunturu