Name the two well-known discretionary attributes.

• A. Local Preference, Atomic Aggregate
• B. Aggregator, Community
• C. Next Hop, Origin
• D. AS Path, Origin

Answer: (A)

In BGP, attributes are categorized as well-known or optional, and as mandatory or discretionary. The two attributes that are well-known yet discretionary are Local Preference and Atomic Aggregate. Local Preference is a locally significant knob inside an AS for choosing the preferred outbound path; it is understood by all BGP speakers but its use is optional and not required to be carried across the entire network. Atomic Aggregate is a flag indicating that route aggregation occurred; like Local Preference, it’s a recognized attribute but its presence is not mandatory and may be omitted in many updates. The other options describe attributes that are either not discretionary or not both well-known; Origin and AS_PATH are well-known and typically mandatory, while Aggregator and Community are not the discretionary pair highlighted here.