Best practices for scanning non-domain devices?

[Joshua]

So I plan on using Lansweeper to keep track of Domain computers (easy with active domain scanning). But I also want it to keep track of our Wyse Zenith Zero Config terminals as well as printers, none of which are on the domain.

This weekend was my big initial scan everything everywhere and with almost 1000 subnets, I didn't realize how slow the scans went. I started with from .1 to .255 and it said it would take about a week to go through it all.

Our DHCP range is from .50 to .126 on each subnet so I first scanned those. Our printers are setup from .150 - .190 so I scanned those next. And the weekend is almost over while I have 10000 IP addresses left in queue.

We can't really scan during the day as it will impact the branches as they only run on T1 and we cannot hurt speed at the counter. Speaking of, is there a way to set active scanning to only hit machines in the middle of the night?

What do you guys do to scan your large networks without impacting network speed at each site?

[Susan_A]

Kris gave some very good tips in his post, the most important one being that you should narrow down your IP ranges as much as possible, under Configuration\Scanning Methods. If the estimated scan time of your ranges is more than a week, I assume you submitted a couple million IP addresses for scanning. The IP scanning procedure is highly optimized and fast, but it's normal for millions of IPs to take several days to finish scanning. Even if a single IP takes just a few seconds, it's still going to take days for the entire range, as there are fewer than 100,000 seconds in a day. Keep in mind the following basic formula for calculating the minimum scan time in days:

number of IP addresses x ping timeout / IP threads / number of seconds in a day (86400)

As Kris mentioned as well, you can increase your IP threads under Configuration\Server Options, though your database can only handle so many simultaneous connections. We wouldn't recommend using more than a couple dozen IP threads. Adding additional scanning servers can spread the scanning load and traffic as well, though adding servers is not supported by your current Lansweeper license. You appear to own a Premium license, which doesn't allow for multi scanning server setups.

Active Scanning cannot be made to run on a fixed schedule. It scans computers as they report to a domain controller. To scan domain computers on a fixed schedule, use a different scanning method instead, e.g. Scheduled Computer Scanning.

[KrisNelson · Accepted solution]

There are ways to make this faster, but would require a lot of configuration if you have 1000 subnets.

Under Configuration go to Scanning Methods (which I'm sure you've already been here). For each of the IP scan ranges use the following tips. But take note of any performance issues that may come from the following changes as they may not work the best, or be practical, in all environments.

Tip 1: The more narrow the range the faster it will scan since it does not have to scan IP's that have nothing on them.

Tip 2: Change the timeout to 1 instead of 4, this will fail unused IP's faster.

Tip 3: Check No Windows for any subnet you know does not have a windows device (printers, wyse terminals, etc). This will skip trying to do any WMI queries which in turns doesn't have to wait for a fail response.

Tip 4: Use the schedule column. You can't tell it to stop at a certain time, but you should be able to set them up well enough that all ranges are done by the time the work day starts.

Tip 5: Under 'Server Options' increase the number of simultaneous IP address scans. Default is 12, 20 should be fine (depending your scanning server). I believe you can increase it higher, but you may not want to.

I do not believe there is a way to stop active scanning during the day (well, supported at least), but you can increase the Minimum Time Between Scans to more than 20 hours so that devices aren't scanned every day. Also increasing the Check Interval from 15 minutes to 30/60 minute or even 4 hours may also help.

An unsupported way to do it would create a scheduled task to start and stop the Lansweeper service so that it is not running during the day. This would force Lansweeper to start a full active scan every time the service started though and may cause more harm than good.

-Kris