Author: Matthew Skelly

Problem:

How to check optimal WAN MTU settings.

Solution:

The primary reason is that in most if not all cases if you send packets at 1500 they will need to be fragmented resulting in degradation of performance. I would not reccomend changing the MTU settings without first checking the optimal settings for your environment, do not just take the word of your ISP, they are making a generalized statement that covers the masses, it is not a total optomization.

Checking is easy to do. First make sure that your MTU setting is in fact 1500 or the test is compromised and will result in a number that is too low.

The command is to see the largest packet is “ping -f -l XXXX www.XXX.com” -f -l forces the ping packet size to be what you specify, any size to lage returns a reply that the packet needed to be fragmented.

-l is a lowwercase L
XXXX is mtu speeds start at 1500 and decrease in multiples of 10 (1500, 1490, 1480 etc…) until you get a ping result, then increase in multiples of 1 until you again get the reply that the packets needed to be fragmented. The highest numbet that did not have to be fragmented is your highest optimal number. I would actually suggest decreasing it by 2. So if 1464 is the highest you could send without fragmentation set the MTU to 1462.

and XXX is a website of your choosing.

Problem:

The User Profile Service failed the logon, loging on with a temporary account

Solution:

In the past, we’ve “fixed” this by creating a new profile and copying all the data from the old one (in the users or documents and settings folder) over to it. However, you can try this registry fix first;

Step 1. To fix the user profile, click Start and type regedit into the search box and press Enter.

Step 2. Registry Editor will launch and you need to navigate to the following key:
HKEY_LOCAL_MACHINESOFTWAREMicrosoftWindows NTCurrentVersionProfileList

Step 3. Click each S-1-5 folder and double-click the ProfileImagePath entry to find out which user account it relates to