How does route poisoning work with holddown timers to prevent routing loops?（）

• A、Information learned from one source is not distributed back to that source.
• B、Routing updates from the poisoned source are ignored until a holddown timer expires.
• C、Failed routes are advertised with infinite metrics.
• D、New routing updates are ignored until the network has converged.
• E、A route is marked as unavailable when its time-to-live is exceeded.