You would expect to see the following output after issuing the show clns neighbors command on RouterA:
System Id Inreface SNPA State Holdtime Type Protocol RouterB Et0/0 0000.0000.000b Up 23 L2 IS-IS

Routers running the Intermediate System to Intermediate System (IS-IS) routing protocol are placed into administrative domains called areas. Each IS-IS router resides in only one area. The collection of all areas managed by a single organization is called a routing domain. RouterA and RouterB are in separate areas, as indicated by the different net commands in their running configurations. RouterA is part of area 49.1741, and RouterB is part of area 48.1741.
Each IS-IS router is configured with a routing level. Level 1 (L1) routers are capable of intraarea routing, which delivers data within a single area. Level 2 (L2) routers are capable of interarea routing, which delivers data between areas. Level 1/Level 2 (L1/L2) routers are capable of both intraarea and interarea routing and maintain a separate linkstate database for each.
You can configure the routing level for an IS-IS process by issuing the istype {level1 | level12 | level2only} command, and you can configure the routing level for an IS-IS interface by issuing the isis circuittype {level1 | level12 | level2only} command. By default, all IS-IS routing processes and interfaces are configured for L1/L2 routing. Therefore, both RouterA and RouterB are configured for L1/L2 routing. Additionally, RouterA and RouterB will establish an L2 adjacency because the routers are in different areas.

If RouterA and RouterB were in the same area, you would expect to see the followingoutput after issuing the show clns neighbors command on RouterA:
System Id Inreface SNPA State Holdtime Type Protocol RouterB Et0/0 0000.0000.000b Up 23 L1L2 IS-IS

If RouterA and RouterB were in the same area and if either router were configured for L1routing only, you would expect to see the following output after issuing the show clns neighbors command on RouterA:
System Id Inreface SNPA State Holdtime Type Protocol RouterB Et0/0 0000.0000.000b Up 23 L1 IS-IS

If RouterA and RouterB were in different areas and if either router were configured for L1routing only, you might see the following output after issuing the show clns neighbors command on RouterA:
System Id Inreface SNPA State Holdtime Type Protocol RouterB Et0/0 0000.0000.000b Up 23 IS IS-IS

L1 routers cannot form adjacencies between areas. When an IS-IS routing level mismatch, authentication mismatch, or maximum transmission unit (MTU) mismatch occurs, an IS-IS adjacency will not form, but the output of the show clns neighbors command might instead show an End System-to-Intermediate System (ES-IS) adjacency. ES-IS is used to discover end systems.