$1.$ Write the full SNMP engine ID for:

a$.$ SNMPv$1$ for a $3$Com hub with the IPv$4$ address $50\mathrm{.}60\mathrm{.}70\mathrm{.}80$ in the $6$th to $9$th octets followed by $0$s from the $10$th octets.

b$.$ SNMPv$3$ for a Cisco router interface with ::$50\mathrm{.}60\mathrm{.}70\mathrm{.}80$ as its IPv$6$ address.$$

$2.$ Access RFC $2274$ and list and define the primitives provided by the authentication module at the sending and receiving security models. Describe the services provided by the primitives.