However, Gary Neville's terrible La Liga run since taking charge of Valencia continued with a 1-0 loss to Sporting Gijon on Sunday -- Los Che's first home defeat since November 2014.
In keeping with their fast starts under new boss Zidane at the Santiago Bernabeu, Madrid raced into a 4-0 half-time lead with Karim Benzema and James Rodriguez's first goal since November adding to Ronaldo's double.
The three-time World Player of the Year sealed his latest La Liga hat-trick nine minutes from time before Oscar Duarte's own goal ensured a repeat scoreline from when the sides met earlier this season.
Victory also moves Real just a point behind local rivals Atletico Madrid after their 2-1 defeat to Barca in a top of the table clash on Saturday.
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However, Barcelona also have a game in hand on both Madrid clubs.
"Our objective is to do our best in every game and get to the end of the season with the chance to win the league," said Zidane.
Zidane's men again made a flying start as Rodriguez's cross from the right picked out Benzema to take his tally for the season to 22 goals in 21 games after seven minutes.
Rodriguez's deflected effort killed the game as a contest after just 18 minutes and Benzema could easily have made it four as he shot wide after a lovely one-two with Isco.
Ronaldo did get the fourth before the break with an audacious piece of skill to skip past Alvaro Gonzalez before blasting into the top corner on his left foot.
In contrast to Zidane's comfortable start to life in La Liga, Neville's Valencia nightmare continued as his winless streak stretched to eight games.
Antonio Sanabria's penalty five minutes into the second-half handed Sporting their first away win since October as Valencia paid for missing a host of clear-cut chances, most notably through captain Alvaro Negredo.
"You're asking me about my position. I find this question ridiculous," said the former Manchester United captain.
"It's from you (the media), don't put this onto the fans." Elsewhere, Sevilla maintained their chase of Villarreal for the fourth Champions League place with their 11th consecutive win at home in all competitions, 3-1 over bottom side Levante.
Celta Vigo missed the chance to move back up to fifth as they conceded a last minute winner to Las Palmas in a 2-1 defeat.