An engineer must configure open SIP Federation on cisco IM and presence using cisco Expressways with the additional requirement not to allow a specific list if domains and allow all other domains that are not specified. How is this additional requirement met?
A. Configure default static routes for each blocked domain with an invalid next-hop IP address.
B. Add a static route for each blocked domain and keep the “Block Route” checkbox checked.
C. Block the specified SIP domains on the Expressway
D. Add each allowed domain as a SIP Federated domain.
C should be correct
Once the static route is configured and unblocked, you cannot block any SIP domains (new or cached) from the IM and Presence node. However, if you include Expressway in your deployment, you can block certain SIP domains on the Expressway itself.
https://www.cisco.com/c/en/us/td/docs/voice_ip_comm/cucm/im_presence/interdomain_federation/12_5_1/cup0_b_interdomain-federation-1251su3/cup0_b_interdomain-federation-1251su3_chapter_010111.html