Using IP Address in Firewall Rules/policies or DNS names

Security experts.  What are you thoughts regarding using IP addresses vs DNS names for destinations in outbound firewall rules/policies.  Any security concerns or performance considerations either way?
James FryEnterprise Solutions ArchitectAsked:
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egarrisonCEO / CTOCommented:
If they are external devices thay you control, then IP is fine.  What you have to watch is companies with DR sites. It is common for companies to have GLB (global load balancers) and tier their sites between multiple data centers.  DNS allows your policy to update when the IP changes. If they use a CDN (content distribution network) then the site may actually live on a large number of IP's.

From a performance standpoint.  DNS lookups have very low overhead.
Joey YungSenior Network EngineerCommented:
From security point of view, most answer are avoid using domain based object if you can, and the main concern I think should regarding DNS spoofing or attack rely on dns query. However, in real case it is not easy to maintain a lot of fixed IP object.

For myself, I will minimum the usage domain based object, and do not use domain based object for inbound traffic from external. Also, place the contain domain based object rules as low as you can.

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