How do you configure AD trusts with external orgs

[bob]

When you set up trusts with outside groups I first verify basic connections between the networks. You test if names resolve properly across the boundaries. I open the management tool on a domain controller and pick the domain node. Then you right click to launch the trust wizard. We choose external trust since it fits separate organizations. I pick two way if both sides need access. Or perhaps one way works better for your case. You enter the other domain name and confirm the password they provide. Also I select forest wide authentication to keep things simple at first. Then you validate the trust right away to catch issues early.
But sometimes DNS causes hiccups so I add conditional forwarders on both ends. You might need to tweak firewall rules for the required ports. I test user access after the trust forms by trying logins from the other side. Perhaps selective authentication comes in handy later if you want tighter control. We skip that initially to get basic function working. Then you monitor event logs for any errors popping up. I adjust the trust properties if validation fails and retry the process. Also you document the settings for future reference since changes happen often.
Now the trust allows resource sharing but I watch for permission problems on shares. You assign rights carefully to avoid over exposure. Perhaps I use netdom commands in scripts for repeats. But you stick to the GUI when training juniors like yourself. I confirm the trust direction matches what both admins agreed on. Then you test group membership across the link to see if it flows. We might need to create special groups for cross access. Also I check for SID filtering and disable it only if required for older systems. You verify with actual file access attempts after setup.
I run into cases where the other org uses different policies so adjustments follow. You prepare by discussing the trust scope beforehand. Perhaps external trusts limit to specific domains rather than full forests. Then we enable the link and confirm with queries. I use tools to query the other side directly. But you avoid complex setups until basics hold steady. Also I restart services if the trust seems stuck. You monitor bandwidth since traffic increases with the new link. We handle upgrades on controllers without breaking existing trusts.
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