H12-891 — frequently asked questions

No. gRPC uses HTTP/2 which can run over plaintext TCP. Encryption is not automatic and requires configuring TLS.

By default, gRPC dial-out transmits data in plaintext over TCP unless TLS is explicitly configured on the device.

If RRs have different Cluster IDs, they may not recognize updates from each other as belonging to the same cluster, potentially leading to routing loops or inefficient route reflection.

No, the Cluster ID is solely for loop prevention. Load balancing is determined by BGP path selection attributes like AS_PATH, LOCAL_PREF, and MED.

No, the inner packet's TTL remains unchanged while the packet is encapsulated within the GRE tunnel. It is only decremented when the packet is decapsulated at the tunnel endpoint.

The problem statement implies the outer TTL is 126 for calculation purposes. In real implementations, the outer TTL might be initialized differently (e.g., 255), but exam questions often provide specific starting values to test the decrement logic.

The three primary components are Authentication Rules, Authorization Rules, and Authorization Results. These define how users are verified and what resources they can access.

Authentication is a verification step that results in a pass or fail status. It does not grant specific attributes or permissions directly; those are handled by the Authorization phase.

In RESTful APIs, POST is used to send data to a server to create a new resource. PUT is generally used to replace an existing resource at a specific URI. Since creation generates a new ID, POST is the standard.

Use POST for creating new managed objects (like adding a new user or interface configuration). Use PUT for modifying existing objects (like changing an IP address or enabling/disabling a feature).

No. OSPF and IS-IS with TE extensions only flood link-state information to build the Traffic Engineering Database (TEDB). They do not have the signaling capability to reserve resources or establish the LSP itself.

RSVP-TE (Resource Reservation Protocol - Traffic Engineering) is the standard protocol used to dynamically signal and establish MPLS TE Label Switched Paths.

If domain IDs do not match, the routes are typically imported as Type 5 LSAs (AS External LSAs) because they are treated as coming from a different autonomous system/domain.

Type 1 LSAs describe router links within an area. Imported BGP routes are not local links; they are summarized or external routes, so Type 1 is incorrect.

Hierarchical topology allows for scalable management of large networks by aggregating traffic through regional hubs before reaching the central core, simplifying policy application and reducing control plane overhead.

Yes, the solution supports partial-mesh and hierarchical structures, allowing administrators to combine full-mesh links for critical paths with hub-spoke connections for general traffic, optimizing both performance and cost.

R1 is likely a Normal Router within Area 0. Only Area Border Routers (ABRs) generate Type 3 Summary LSAs to advertise routes between areas.

It represents the default route (0.0.0.0/0) being advertised by the ABR into the area. The question excludes this, asking for specific subnet advertisements.

In most standard regular expression engines, the dot metacharacter matches any single character except newline.

The pattern requires exactly one character after '100' before the string ends. 100 has no characters after the prefix, making it too short.