Network Troubleshooting

Important to find out: Is just one person having a problem, or are multiple people losing connectivity? Is a whole building down?

OS-specific network troubleshooting tips

Network Troubleshooting - Windows

Network Troubleshooting - Mac OS X

Rogue Servers and/or entire building losing connectivity

  1. Note that one person calling with connection issues doesn’t mean the whole building is down. Ask the customer if anyone else is having the same issue. Generally we need a few calls to consider the issue to be building wide.
  2. Talk to someone in SR immediately. Also make a ticket assigned to SR.
  3. If this happens after 5pm, check “SNS After Hours” (it’s a Public Folder/Calendar in Outlook) and call the person listed there. Be prepared to give all the information you would put in a ticket. Still make a ticket and indicate whether you have contacted someone about the problem.

Decoding IP addresses

We can get a little information about the computer's network status by looking at the first two sections of its IP address.

  • 140.233... Computer should have a normal connection.
  • 172.17 is the registration subnet. 172.19 is the penalty subnet; 172.18 is the quarantine subnet; 172.16 is connected to midd_secure; 172.20 is midd_unplugged.
  • 169... Computer can’t find our DHCP server. See specific OS steps to clear any static-IP settings and flush DNS.
  • 192... or 10… (BAD addresses for on-campus, may be OK for off-campus, see footnote [1]). May indicate a manual IP address or rogue DHCP server. Create a new location, reboot. If it still gets a 192… or 10… IP address, there may be a rogue DHCP server in that subnet/area. See above.
  • Other messages or unclear symptoms - Invite the customer to LIB202 to see if the problems persist in another location.

I've put this troubleshooting page at the top level, as it is likely to be the most frequently used troubleshooting page.

--Mitrevski, Petar 13:20, 11 July 2008 (EDT)

  1. Some off-campus college houses are supposed to have 192 or 10 addresses. Knowledgebase has a list of off-campus locations.