Which method could be used to improve the scalability of IS-IS used as the IBGP of an ISP?
A. Use stub or totally stubby nonbackbone IS-IS areas.
B. Use IS-IS route leaking into the nonbackbone IS-IS areas.
C. Use IS-IS CSNP on Level-1-2 circuits.
D. Use IS-IS pseudo-node on Level-1-2 circuits.
E. Use proper interarea route summarization.
F. Use proper external route summarization when redistributing BGP routes into IS-IS.
