141. Which command converts a replica set to a sharded cluster?

• a) sh.addShard()
• b) mongos --convert
• c) No single command (multi-step process)
• d) db.convertToSharded()

142. What is the purpose of the $dayOfYear operator?

• a) Returns day number (1-366)
• b) Calculates year progress
• c) Groups by fiscal year
• d) Validates year length

143. Which method configures MongoDB Atlas Triggers?

• a) Atlas UI/API only
• b) db.createTrigger()
• c) mongod --triggers
• d) db.triggers.setup()

144. What does the $ifNull operator do?

• a) Returns alternative if expression is null
• b) Checks for null documents
• c) Validates non-null fields
• d) Filters null values

145. Which operator performs element-wise array comparison?

• a) $cmp
• b) $compareArrays
• c) $arrayCmp
• d) $eq

146. What is the purpose of the $addFields stage?

• a) Adds new fields to documents
• b) Creates collections
• c) Merges documents
• d) Extends schemas

147. Which command lists MongoDB's storage engines?

• a) db.serverStatus().storageEngine
• b) show engines
• c) db.listEngines()
• d) mongod --listEngines

148. What does the $substrBytes operator do?

• a) Extracts substring by byte length
• b) Counts bytes
• c) Validates UTF-8
• d) Splits binary data

149. Which method returns MongoDB's sharding status?

• a) sh.status()
• b) db.shardingInfo()
• c) mongos --status
• d) db.getShardingState()

150. What is the purpose of the $dateFromParts operator?

• a) Constructs date from components
• b) Extracts date segments
• c) Validates partial dates
• d) Converts timezones

151. Which operator checks array position conditions?

• a) $position
• b) $arrayElemAt
• c) No direct operator (use $slice + $arrayElemAt)
• d) $index

152. What does the $stdDevSamp operator return?

• a) Sample standard deviation
• b) Population standard deviation
• c) Statistical mean
• d) Variance estimate

153. Which command lists all shards in a cluster?

• a) db.adminCommand({ listShards: 1 })
• b) sh.listShards()
• c) db.shards()
• d) show shards

154. What is the purpose of the $split operator?

• a) Divides string by delimiter
• b) Partitions collections
• c) Separates shard chunks
• d) Splits binary data

155. Which operator checks if all array elements are true?

• a) $allElementsTrue
• b) $all
• c) $and
• d) $every

156. What does the $sum operator do in $group?

• a) Calculates arithmetic sum
• b) Counts documents
• c) Aggregates totals
• d) Validates numbers

157. Which method returns MongoDB's connection pool stats?

• a) db.serverStatus().connections
• b) db.connectionPool()
• c) mongod --connections
• d) db.poolStats()

158. What is the purpose of the $concat operator?

• a) Joins strings end-to-end
• b) Merges arrays
• c) Combines collections
• d) Links documents

159. Which operator checks if any array element is true?

• a) $anyElementTrue
• b) $or
• c) $some
• d) $in

160. What does the $strLenBytes operator return?

• a) String length in bytes
• b) Character count
• c) UTF-8 validity
• d) Binary size