Following stints at California Lutheran and Delta State University, in 2008 he was tapped by his mentor, Greg McMackin, to serve as the defensive line coach for the University of Hawaii Warriors. In Aranda's first season, he cultivated a talented unit that included David Veikune, Joshua Leonard and Keala Watson. In 2009, Aranda was credited with developing a creative defensive scheme that stymied Navy's vaunted rushing attack and allowed the Warriors to earn a 24–17 victory In those wins, his opportunistic defense limited the opposition to 16.1 points per game, only allowed 2.4 yards per rush over a Midshipmen squad that defeated Notre Dame two weeks earlier. The following year he was elevated to Defensive Coordinator. He helped lead the Warriors to victory in nine of their last ten regular season games. In those wins, Aranda's opportunistic defense limited the opposition to 16.1 points per game, only allowed 2.4 yards per rush and held Colin Kapernick in check en route to handing the Nevada Wolfpack its only loss of the season. Under Aranda's guidance the Warriors led the nation in turnovers caused and tied a school record for most defensive touchdowns. Although the Warriors struggled to a 6–7 record in 2011, Aranda's defense was particularly impressive in a 34–17 drubbing of Colorado. Leading up to the game, Colorado coach Jon Embree boasted that as to Hawaii's defense, the Buffaloes were going to "run the ball down their throat." Aranda, who later acknowledged that he took Embree's comment personally, met the challenge head on and limited the boastful Buffaloes to just 17 net rushing yards on the night. For the year, Aranda's defense led the Western Athletic Conference and was tied for 15th in the FBS in sacks. At the conclusion of the season, he found himself on the wrong-side of the ledger and was fired after head coach Greg McMackin resigned. Despite the circumstances, Aranda said later "I miss the family atmosphere there. I miss the people."
Utah State
In 2012, Aranda was the Defensive Coordinator for one year for the Utah State Aggies under Gary Andersen. That same year he was a nominee for the Broyles Award as the Aggies defense finished in the top 15 of all FBS schools in all four major defensive categories; seventh in scoring defense, 13th in rushing defense, eighth in pass-efficiency defense and 14th in total defense.
Wisconsin
When Gary Andersen was hired as the new Wisconsin Badgers head coach, following the 2012 football season, Aranda followed him to Wisconsin. Aranda turned down offers from Texas Tech and California. Aranda changed the Badgers' base defense from a 4–3 to a 3–4 and developed a more aggressive defense, putting pressure on the quarterback. His first year as Defensive Coordinator the Badgers defense ranked in the top 20 in all four major defensive categories; scoring defense, total defense, rushing defense and passing defense. Week 10 of the 2014 football season Aranda was named Coordinator of the Week by Athlon Sports after his Wisconsin Badgers defense shutout Rutgers Scarlet Knights 37–0. It was Wisconsin's first road shutout since 1998. The Badgers took 1st place in the West Division with a 10–2 record, going 7–1 in the conference. Wisconsin played Ohio State for the conference title in the 2014 Big Ten Championship Game where the Badgers lost to Ohio State 59–0. It was the first time since 1997 that the Badgers were shutout and the worst loss since 1979 when Ohio State also defeated the Badgers 59–0. Four days after the Badgers lost to Ohio State, Gary Andersen departed Wisconsin for Oregon State. Former Badgers offensive coordinator and Pitt head coach, Paul Chryst, was hired as the next head coach of the Badgers. Aranda was the only assistant coach to remain on the coaching staff after Andersen's departure. Two of Aranda's three years at Wisconsin one of his linebackers won the Big Ten Linebacker of the Year, Chris Borland in 2013 and Joe Schobert in 2015. Borland also won Big Ten Defensive Player of the Year in 2013. Aranda alongside his OLB coach Tim Tibesar were named Linebacker Coaches of the Year for 2015 by FootballScoop. Over Aranda's three-year span as defensive coordinator at Wisconsin his defense ranked first nationally in total defense, second in scoring defense, third in pass defense and fourth in run defense. His final season with the Badgers his defense came in first in scoring defense, allowing just 13.1 points per game.
LSU
On January 1, 2016, it was announced that Aranda was hired to replace Kevin Steele as defensive coordinator for the LSU Tigers. The move to LSU saw his starting salary nearly triple from $520,000 to $1.3 million. His contract is guaranteed for three years and is not tied to the contract of LSU head coach Ed Orgeron. On January 5, 2018, it was announced that Aranda received a new four-year contract that will pay him $2.5 million annually and the entire $10 million deal is guaranteed. This was in response to several attempts by Texas A&M to hire Aranda.
Baylor
On January 16, 2020, Aranda was named the head coach at Baylor University, replacing Matt Rhule who left to become the head coach of the Carolina Panthers.
Statistics
Team defensive statistics where Aranda was defensive coordinator.
Personal life
David and his wife Dione have 3 children, two daughters Jayden and Jordan, and a son Ronin.
