Exam 300-620 topic 1 question 141 discussion

Create the 0.0.0.0/0 subnet. Because Create 128.0.0.0/1: This only covers the second half of the IPv4 address space (128.0.0.0 to 255.255.255.255) and does not include 10.1.0.0/24, which falls in the first half.

Hard question Adding internal EPGs and External EPGs (associated to L3Outs) to the Preferred Group allows to enable free east-west and northsouth connectivity - When adding the Ext-EPG to the Preferred Group: • Can’t use 0.0.0.0/0 for classification, needs more specific prefixes As workaround it is possible to use 0.0.0.0/1 and 128.0.0.0/1 to achieve the same result. https://www.ciscolive.com/c/dam/r/ciscolive/global-event/docs/2022/pdf/BRKDCN-2480b.pdf

I vote b

Answer is B - https://www.cisco.com/c/en/us/td/docs/switches/datacenter/aci/apic/sw/4-x/L3-configuration/Cisco-APIC-Layer-3-Networking-Configuration-Guide-401/Cisco-APIC-Layer-3-Networking-Configuration-Guide-401_chapter_011000.html

Answer is B - https://bst.cloudapps.cisco.com/bugsearch/bug/CSCve28564 https://unofficialaciguide.com/2017/10/24/transit-routing-use-case-eigrp-with-routed-interfaces/ When the L3 Out Network EPG has 0.0.0.0/0 as a prefix entry, "Preferred Group Member" Include is not configurable - One workaround is to break 0.0.0.0/0 to 0.0.0.0/1 and 128.0.0.0/1 The correct Answer is B

According this ACI allows whole range 0/0: "As part of the L3Out configuration, these subnets should be defined as external networks. Alternatively, an external network could be defined as 0.0.0.0/0 to cover all possible destinations." https://www.networklife.net/images/sheets/Networklife_CheatSheet_ACI_04_L3out_v1.1.pdf

We have preferred groups running, so the external network should be splitted

B is right ACI does not allow whole range 0.0.0.0/0 , so required split ranges.

B - is more granular The 0.0.0.0/0 matches every IP address, whereas 0.0.0.0/1 only matches half of them (0.0.0.0-127.255.255.255) and requires 128.0.0.0/1 as its pair to match the rest (128.0.0.0-255.255.255.255). https://serverfault.com/questions/1100250/what-is-the-difference-between-0-0-0-0-0-and-0-0-0-0-1

its C, this allows any subnet to communicate with internal EPGs (given the right contracts of course). Those two subnets in the screenshot dont even make any sense at all.

is this not C?? https://unofficialaciguide.com/2019/11/08/understanding-scope-of-prefixes-in-l3-out-external-epg-in-aci/