Exam 350-401 topic 1 question 58 discussion

im here just to remember answer, if they want me to do hex maths in my head on the exam then they lost their mind.

The Option 43 hexadecimal string is assembled as a sequence of the TLV values for the Option 43 suboption: Type + Length + Value. Type is always the suboption code 0xf1. Length is the number of controller management IP addresses times 4 in hex. Value is the IP address of the controller listed sequentially in hex. On this question, there is 1 controller with management interface IP addresses 172.16.50.5/24. The type is 0xf1. The length is 1 * 4 = 8 = 0x04. The mgmt IP addresses 172.16.50.5 translate to ac.10.32.05 (0xac103205). When the string is assembled, it yields f108c0a80a05c0a80a14. The Cisco IOS command that is added to the DHCP scope is: option 43 hex f104ac103205

The hex string is assembled by concatenating the TLV values shown below: Type + Length + Value (1) The type is always f1(hex): F1 (2) Length is the number of controller management IP addresses times 4 in hex: We have a single WLC with a single management IP address ---> 1 x 4 = 4 = (04) in hex represented as 2 hex digits. (3) Value is the IP address of the controller listed sequentially in hex: 172.16.50.5 = AC10.3205 172 ---> AC 16 -----> 10 50 -----> 32 5 -------> 05 configure option 43 Hex F104.AC10.3205 https://www.cisco.com/c/en/us/td/docs/wireless/access_point/1550/installation/guide/1550hig/1550_axf.pdf

A is correct

#python3 ip_addr = [int(i) for i in '172.16.50.5'.split('.')] print(ip_addr) for i in ip_addr: print(f'dec={i}, hex={str(hex(i))[2:]}') #output: [172, 16, 50, 5] dec=172, hex=ac dec=16, hex=10 dec=50, hex=32 dec=5, hex=5

check this article how to convert option 43 hexidecimal. https://www.rapidtables.com/convert/number/hex-to-decimal.html?x=F104 Option 43 IP to hexi converter https://shimi.net/services/opt43/

Using ASCII characters for the IP address are only supported for the older Cisco 1000 series APs, all the rest require HEX characters

shimi.net/services/opt43 Vendor Cisco: f1 (hex) IP count: 1 IP count * 4 bytes = 4 ---> 04 (hex) 172.16.50.5 = ac103205 (hex) option 43 hex f104.ac10.3205

provided answer is correct

I dont get it, shouldn't the "Option 43 Ascii 172.16.50.5" work? Why we have to use hex option here?

The answer provided is correct https://www.cisco.com/c/en/us/td/docs/wireless/access_point/1550/installation/guide/1550hig/1550_axf.pdf

voting. provided answer is correct