These crawls are part of an effort to archive pages as they are created and archive the pages that they refer to. That way, as the pages that are referenced are changed or taken from the web, a link to the version that was live when the page was written will be preserved.Then the Internet Archive hopes that references to these archived pages will be put in place of a link that would be otherwise be broken, or a companion link to allow people to see what was originally intended by a page's authors.The goal is to fix all broken links on the web . Crawls of supported "No More 404" sites. 

 When Alaskan teen David Grunwald didn't return home last Sunday night, his family immediately thought something was wrong. 
 
 David Grunwald Cheri Ruiz 
 
 And when his 1995 Ford Bronco was discovered abandoned and torched on a rural trail several hours later, panic set in. 
 
 "I think they are holding up as best as can be expected," Brenda Paradise, a private investigator working on the case, told Dateline. "They are preparing for the worst, but we're praying for a miracle." 
 
 David was last seen dropping off his girlfriend, with whom he had spent the day, on Sunday, November 13 around 6:30 p.m. at her father's home in Palmer. The 16-year-old then called his mother saying he had plans to stop by a friend's house and might not be home to make the agreed-upon 9:00 p.m. curfew. But he told her he wouldn't be more than 20 minutes late. 
 
 The friend never saw David. And David never returned home. His mother reported him missing around 11:45 p.m. 
 
 The next day, David's Bronco was discovered on a rough trail popular with four-wheelers on Bald Mountain Ridge, roughly a 20-minute drive from his family's home. The car was so badly burned, metal pieces had fallen off and no material was left inside. No remains were found in or around the vehicle, according to police. The rural area surrounding the site was searched, but David was nowhere to be found. 
 
 David Grunwald's 1995 Ford Bronco was found abandoned and burned. Alaska State Troopers 
 
 On Friday, Paradise, a private investigator for a non-profit group, joined the efforts to find the team after being phoned by another Alaskan organization assisting on the case. Paradise, whose organization provides services pro-bono, told Dateline there is a massive effort to find David. "Really, this could have been anyone's kid, which is why there has been such an outpouring of people wanting to help," Paradise said. 
 
 On Monday Megan Peters, spokesperson for the Alaska State Troopers, told Dateline there have been no updates to the case. Although no official searches are being held at this time, in an effort to establish a more solid timeline of the David's movements, authorities are seeking anyone who may have seen the teen or his Bronco being driven after 7:00 p.m. that Sunday evening 
 
 For David's loved ones, it's an unimaginable situation in which to find themselves. 
 
 "We are desperate for any information to locate David. This is a living nightmare," Cheri Ruiz, David's aunt, told Dateline. "We need him home. We need to locate him and help him." 
 
 David, a junior at the Mat-Su Career and Technical High School, is described as an all-America teen with a close-knit group of friends. The teen, who comes from a military family, has aspirations to become a pilot and possibly join the military himself someday. There were no obvious signs that anything was bothering him in his life. 
 
 "I'm not seeing any signs or red flags in this case," Paradise told Dateline. "It very well could be a case of wrong place, wrong time, wrong people." 
 
 More than 300 volunteers, many active-duty military personal or National Guard members, met up Saturday to search and hang fliers, family members said. Because of the rough terrain and with temperatures dipping into the teens overnight, officials are asking for volunteers not to head out on their own to searches. 
 
 Paradise, who helped organize and oversee the search effort this weekend, told Dateline they are not releasing much information regarding the areas her organization and law enforcement are focusing on, so as not to jeopardize the investigation in any way. 
 
 She is also encouraging anyone who may have information in the case to call in, and to not be afraid to talk with authorities. There is now a third-party anonymous tip line anyone with information can call or text to that will be sent to police. An expert, who has previously worked with the FBI, flew in late last night, and Paradise hopes answers will be found in the next few days. 
 
 David's loved ones are extremely grateful for all the support they've received, and are holding on to hope he will be brought home soon. 
 
 "David is missed immensely and we need him home," David's aunt Cheri said. 
 
 David Grunwald is described as 6' tall, weighing 150 lbs. with brown hair and blue eyes. He was last seen wearing an orange North Face jacket, jeans and moccasin-style shoes. 
 
 Anyone with information regarding his whereabouts is urged to call the Alaska State Troopers at (907) 352-5401 or Private Investigator Brenda Paradise at (281) 642-7299. You can also call or text the anonymous tip line for the case at (907) 290-8999. 

 Hundreds volunteered on Saturday to help look for a 16 year old teenager who has been missing for nearly a week. 
 
 Hundreds of volunteers gather in Palmer to search for a missing 16 year old teenager. 
 
 David Grunwald was last heard from Sunday night when he told his mother he'd be late after dropping his girlfriend off at the Butte. 
 
 Grunwald's bronco was found burned up a day later. 
 
 Brenda Paradise, a search organizer who works for Guardian Search and Investigations said volunteers are combing through the woods, from the air and local businesses to find any trace of Grunwald. 
 
 "We're putting boots on the ground to see if we can get some information that might lead to getting this boy found and come home," Paradise said. 
 
 Volunteers spread flyers with Grunwald's photo and number to contact local law enforcement agencies around Wasilla and Palmer businesses. 
 
 Renae Turner, a volunteer said Grunwald is a member of her church. 
 
 "He's a very good kid, he and his family, we love 'em," Turner said. "David attends our church and so he's a part of our family and so we're really concerned about him and want him to be found." 
 
 While Grunwald remains missing, Paradise said Saturday afternoon searchers found some leads and will continue looking for any trace of Grunwald. 
 
 Anyone with any information or who may have seen Grunwald or his vehicle on Sunday evening is asked to call Alaska State Troopers at 907-352-5401.
– A massive search effort in Alaska has failed to find any trace of David Grunwald, a 16-year-old who vanished more than a week ago. He was last heard from the evening of Sunday, Nov. 13, when he called his mom to say he'd be back a little late from dropping his girlfriend off, KTUU reports. He was reported missing by 11pm and the next day, his burned Ford Bronco was found on a trail up Bald Mountain Ridge, about a 20-minute drive from his parent's home in Palmer. David is from a military family, and service members were among around 300 people who joined search efforts in rough terrain over the weekend, Alaska Dispatch News reports. Six horse teams and a helicopter joined the effort around Palmer, which is about 40 miles away from Anchorage. No remains were found in or around the badly burned Bronco. David's relatives "are holding up as best as can be expected," private investigator Brenda Paradise tells NBC. "They are preparing for the worst, but we're praying for a miracle." She says there's no sign that anything was bothering David. "It very well could be a case of wrong place, wrong time, wrong people," she says. Paradise, who's providing her services pro bono, tells the Dispatch News that an anonymous tip line (907-290-8999) has been set up. "A lot of people are afraid to call law enforcement; a lot of people are afraid to get involved because there's minors involved," she says. (Elsewhere, a ransom has been offered in the case of a missing jogger.)