1) Type or paste your list of IP addresses into a single column within Microsoft Excel (this writeup assumes you use column A);
2) Select the cells that contain IP addresses;
3) Click or select Text to Columns under the Data tab in the menu;
4) Choose ‘Delimited’ as your file type and click Next;
5) Select ‘Other’ as the delimiter and insert a period in the open field, and select Finish (not Next);

That should split each individual IP address into 4 separate columns (columns A through D), allowing you to Sort them by following these steps:
1) Select the 4 columns by clicking on the column header for column A and dragging to select all 4 columns before releasing your mouse button;
2) Click the Data tab in your menu and select ‘Sort’;
3) Here you can choose among a variety of sorting options, including smallest to largest;

After you sorted the IP list of IP addresses, you can use a formula to combine the cells while inserting a period to separate the values:
1) Type the following formula in column E, Row 1:

=A1&”.”&B1&”.”&C1&”.”&D1

2) Double click click the tiny square that appears in the border of the cell in Column E, Row 1, filling the other cells within Column E with this formula;
3) You can always copy Column E and paste values using the paste special function in Excel.