On both 7.9 and 8.0 what you probably have to do is import the AD certificate (and possibly any intermediate certificates) into Java’s cacerts keystore.
If you’re on 7.9 this is gonna be in lib/security wherever Java is installed, and probably needs to be re-imported every time you update Java.
On 8.0 you just drop it into the data/certificates/supplemental folder wherever Ignition is installed and restart Ignition (or wait, maybe?) and it should get imported into the distributed runtime’s keystore automatically.