Exam 200-301 topic 1 question 130 discussion

B is correct. Question gave 3 hints to work on. (RoS, VLAN 3, and /23) RoS require matching VLAN ID which is 3 and /23 = 254. So dot1Q=3 and 255.255.254.0 = B Hope this help

They threw a curve ball. What you name the sub interface doesn't matter, although it is not best practice doesn't follow logic, as long as you have the correct encapsulation and ip address configured.

You need to create another subinterface for VLAN 3 with its corresponding default gateway.

It is option B. interface GigabitEthernet0/0.10 encapsulation dot1Q 3 ip address 10.10.2.10 255.255.254.0 Let me break it down... --> The gig0/0.10 is a sub interface and need not match with the VLAN ID, it could be any arbitrary number. --> encapsulation dot1Q vlan 3 specifies configuration for vlan 3 --> subnet mask has already been given --> 255.255.254.0 --> config for VLAN 2 has already been configured and the option we are choosing is for VLAN 3 now, both VLAN 2 and 3 has been configured on the router to facilitate communication So, it is Option B

B is correct

you would think cisco questions would be conceptual but instead they are tricky

I don't think they need to ask such tricky questions.

Answer is B R1 Subinterface Configuration (4.2.4) The router-on-a-stick method requires you to create a subinterface for each VLAN to be routed. A subinterface is created using the interface interface_id.subinterface_id global configuration mode command. The subinterface syntax is the physical interface followed by a period and a subinterface number. Although not required, it is customary to match the subinterface number with the VLAN number. https://www.ciscopress.com/articles/article.asp?p=3089357&seqNum=5