A Reader account in Snowflake can be used to share data with a consumer who does not have a Snowflake account. Reader accounts are a type of shared account provided by data providers to external data consumers, allowing them to access and query shared data using Snowflake's web interface without needing their own Snowflake account.
Reference:
Snowflake Documentation: Reader Accounts

Snowflake's default Multi-Factor Authentication (MFA) service is powered by Duo Security. Users are required to install the Duo Mobile application on their devices to use MFA for increased login security when connecting to Snowflake. This service is managed entirely by Snowflake, and users do not need to sign up separately with Duo1.

When a CLUSTER BY clause is added to a Snowflake table, it specifies one or more columns to organize the data within the table's micro-partitions. This clustering aims to colocate data with similar values in the same or adjacent micro-partitions. By doing so, it enhances the efficiency of query pruning, where the Snowflake query optimizer can skip over irrelevant micro-partitions that do not contain the data relevant to the query, thereby improving performance.
Reference:
Snowflake Documentation on Clustering Keys & Clustered Tables1.
Community discussions on how source data's ordering affects a table with a cluster key

The list @my_stage command in Snowflake can be used to verify if data has been uploaded to an external stage named my_stage. This command provides a list of files that are present in the specified stage2.

Snowflake's Fail-safe provides a 7-day period during which data in a permanent table may be recoverable, but only by Snowflake Support, not by user operations3.