We have 120 users on network with cyberoam ( 50 ING ) firewall configured , from last 2 weeks we had issues like http websites not resolving getting error could not reach . But on other ISP it works fine.
Cyberoam 50 ING Firewall with BSNL ISP configured ....connected to Unmanaged switches
Internal AD integrated with DNS Server windows 2012 r2
All server + clients having primary dns server is windows server local IP address
But if do the nslookup domain name then it resolves fine but on browser it stucks. But sometime it works fine too.
ipconfig / flushdns
ipconfig / release
ipconfig / renew
ipconfig / registerdns
Antivirus scan + malware scan , after malware scan it works for sometime and again it stucks. some of PC having the malware or spyware which blocks the http 80
everything did but http is not working . Only remains the Cyberoam Firewall firmware upgrade and restart of Windows 2012 server.
Please assist me to resolve this issue on urgent basis