[closed] DNS / two NIC’s

hi guys,

first of all, I'm not sure whether this is the right place to ask but let my ask the question anyway. i use VMware ESXi host to build my lab. in vSphere i've created two separate networks 10.0.0.0/8 192.168.0.0 /24 both are internal networks without internet access. between both i have a VyOs VM as a virtual router to connect both networks. in each site i have a DC and Exchange - mail between both domains working just fine. when i add on any of those VM's a second NIC (internet facing ) mails are not getting delivered. i'm not even ping the other domain at this time. i think that as soon the second NIC is up each single DNS query is processed by the DNS server obtained by DHCP. now when i do route print inside the VM i see two route entries pointing to the default route 0.0.0.0 , one pointing to the "internet" NIC with a metric of 50 and the other pointing to the "internal"interface with a metric of 266. i know that my Exchange is not configure to receive / send mails to the outside world because of missing MX etc. but just to have it still working internally while the "internet" NIC is also up would it be enough to change the metric the other way around ?

thank you very much !

regards

ADam