Assuming Jennifer is moving over the public Internet (that her Haven isn't close enough for wireless/WiFi access), Avalon's public site isn't difficult to find. There are a couple of links to off-site services such as OpenTable and Yelp, and she notices that it uses an IP assigned to Comcast.
Jennifer can attempt to penetrate the site itself to see if it's actually hosted at Avalon, or at an ISP. She can also attempt to hack OpenTable or Yelp for access, or go straight into Comcast.
Any of these options will be an Extended and Contested Action: she may roll a number of rolls equal to her pool per standard Extended Acton limits -- in this case, seven rolls of seven dice. Each roll will represent an hour of effort and will be compared against the successes rolled of the sysop(s) of the defending system.