Question

refer to the image. an administrator has constructed a backup schedule for their machine. their computer crashes on wednesday and they need to fully restore their data. apart from the full backup on sunday, which day needs to be restored? the image shows a table with columns labeled s (sunday), m (monday), t (tuesday), w (wednesday), t (thursday), f (friday), s (saturday). the second row lists backup types: full (s), differential (m), incremental (t), differential (w), incremental (t), differential (f), (s is empty).

Explanation:

Step1: Understand Backup Types

Full backup (Sunday) is the base. Differential backup includes all changes since the last full backup. Incremental includes changes since last backup (any type).

Step2: Analyze Wednesday's Restore

Wednesday has a Differential backup. To restore Wednesday, after Sunday's full, we need the latest differential before/on Wednesday. Monday is Differential, but Wednesday's Differential includes changes up to Wednesday (since last full on Sunday). Wait, no—Differential backup on a day includes all changes from last full (Sunday) up to that day. So for Wednesday, the differential backup on Wednesday itself? Wait, the table: Sunday (Full), Monday (Differential), Tuesday (Incremental), Wednesday (Differential), Thursday (Incremental), Friday (Differential). Wait, no—wait, the problem is the computer crashes on Wednesday. So to restore, we need the full (Sunday) and the latest differential before Wednesday? Wait, no: Differential backup on a day captures all changes since the last full. So Monday's Differential: changes from Sunday to Monday. Wednesday's Differential: changes from Sunday to Wednesday. So if the crash is on Wednesday, after Sunday's full, we need to restore the Differential backup from Wednesday? Wait, no—the table shows Wednesday as Differential. Wait, maybe I misread. Wait the table: columns S (Sunday: Full), M (Monday: Differential), T (Tuesday: Incremental), W (Wednesday: Differential), T (Thursday: Incremental), F (Friday: Differential), S (Saturday: empty). So when the computer crashes on Wednesday, to restore, we need the full backup (Sunday) and the differential backup from the last differential before or on Wednesday? Wait, no—Differential backup on a day includes all changes since the last full. So Monday's Differential: up to Monday. Wednesday's Differential: up to Wednesday. So if the crash is on Wednesday, after restoring Sunday's full, we need to restore the Differential backup from Wednesday? Wait, but the question is "apart from the full backup on Sunday, which day needs to be restored?" Wait, maybe the key is that Differential backup on Wednesday is the one that includes all changes from Sunday to Wednesday. Wait, no—wait, the backup schedule: Sunday is full. Then Monday: differential (changes since Sunday). Tuesday: incremental (changes since Monday). Wednesday: differential (changes since Sunday). Wait, no, that's not how differential works. Wait, no—Differential backup always includes all changes since the last full backup. So each differential backup is cumulative from the last full. So Monday's differential: changes from Sunday to Monday. Wednesday's differential: changes from Sunday to Wednesday (including Monday and Tuesday). So if the computer crashes on Wednesday, to restore, we need Sunday's full and then the latest differential backup before or on Wednesday. The latest differential before Wednesday is Monday? No, Wednesday's differential is on Wednesday. Wait, the table shows Wednesday as Differential. So the crash is on Wednesday, so the backup on Wednesday is the differential. Wait, maybe the problem is that when using differential backups, you only need the last differential after the full. So Sunday (full), then the next differential is Monday, then Wednesday, then Friday. But if the crash is on Wednesday, the latest differential before Wednesday is Monday? No, Wednesday's differential is on Wednesday. Wait, maybe I'm overcomplicating. Let's look at the table again:

Days: S (Full), M (Differential), T (Incremental), W (Differential), T (Incremental), F (Differential), S (empty).

Crash on Wednesday. To restore, we need the full (Sunday) and then the differential backup that includes all changes up to Wednesday. The differential backups are on Monday, Wednesday, Friday. The one on Wednesday is the latest differential before/on Wednesday. Wait, but the question is "apart from the full backup on Sunday, which day needs to be restored?" Wait, maybe the answer is Wednesday? No, wait—wait, when you have a full backup (Sunday) and then differential backups, each differential includes all changes since the last full. So to restore Wednesday, you need Sunday's full and then the differential backup from Wednesday (since it includes all changes up to Wednesday). But wait, maybe the key is that incremental backups are based on the last backup (any type), but differential is based on last full. So if the crash is on Wednesday, after Sunday's full, the differential backup on Wednesday is the one that has all changes from Sunday to Wednesday. So apart from Sunday, we need to restore Wednesday's differential? Wait, but the table shows Wednesday as Differential. Alternatively, maybe the answer is Monday? No, that doesn't make sense. Wait, let's think again. The full backup is Sunday. Then Monday: differential (changes from Sunday to Monday). Tuesday: incremental (changes from Monday to Tuesday). Wednesday: differential (changes from Sunday to Wednesday). So if we restore Sunday's full, then Wednesday's differential, that would include all changes up to Wednesday (since differential is from last full). The incremental on Tuesday is based on Monday's differential, so if we use Wednesday's differential, we don't need Tuesday's incremental. So the answer should be Wednesday? Wait, but the question is "apart from the full backup on Sunday, which day needs to be restored?" Wait, maybe I made a mistake. Wait, the backup schedule: Sunday (Full), Monday (Differential), Tuesday (Incremental), Wednesday (Differential), Thursday (Incremental), Friday (Differential). So when the computer crashes on Wednesday, the data up to Wednesday is in Sunday's full + Wednesday's differential (since differential includes all changes from Sunday to Wednesday). The incremental on Tuesday is only changes from Monday to Tuesday, but Wednesday's differential already includes that (since it's from Sunday to Wednesday). So we don't need Tuesday's incremental. So apart from Sunday, we need to restore Wednesday's differential? Wait, but the table shows Wednesday as Differential. So the answer is Wednesday? Wait, no—wait, maybe the answer is Monday? No, that can't be. Wait, let's check the backup types again. Differential backup: backs up all files that have changed since the last full backup. So each differential backup is a cumulative backup from the last full. So Monday's differential: changes from Sunday to Monday. Wednesday's differential: changes from Sunday to Wednesday (including Monday and Tuesday). So if the crash is on Wednesday, after restoring Sunday's full, we need to restore the latest differential backup before or on Wednesday, which is Wednesday's differential. So the day to restore apart from Sunday is Wednesday. Wait, but the table's Wednesday column is labeled "Differential". So the answer should be Wednesday? Wait, maybe I'm wrong. Wait, maybe the key is that incremental backups are only needed if you use incremental, but differential is cumulative. So in this case, the backup on Wednesday is differential, so to restore Wednesday, you need Sunday (full) and Wednesday (differential). So the answer is Wednesday.

Answer:

Wednesday