With IPHost Network Monitor you can run simple snmp requests against a Cisco device in your network.
cnrNotifDnsServerIpAddress
cnr Notif Dns Server Ip Address
1.3.6.1.4.1.9.9.120.1.2.15
The IP address of the DNS server.
Back to CISCO-NETWORK-REGISTRAR-MIB MIB page.
IPHost Network monitor allows you to monitor cnrNotifDnsServerIpAddress on Cisco device via the SNMP protocol. Download IPHost Network Monitor (500 monitors for 30 days, 50 monitors free forever) to start monitoring Cisco switches right now.