The 24-year-old France international is now in the last six months of his contract at the Ligue 1 club and attracting plenty of interest.
Wolfsburg were believed to be in advanced negotiations to sign Ntep earlier this week as they look to fill the hole in their squad left by the departure of Julian Draxler to Paris Saint-Germain.
However, sources in France claim Palace are looking at the Rennes forward, who almost signed for Queens Park Rangers in January 2014.
The south London club are set to make multiple signings in the January window as Sam Allardyce looks to improve the squad after being appointed Eagles boss last month.
“We’re lacking in a few areas, so we need to try and fix that,” chairman Steve Parish told Holmesdale Radio recently.
“We’re moving heaven and earth to do the things we need to do to support the manager and support the team.”
Ntep has scored two goals in 14 Ligue 1 starts for Rennes this season.
Nottingham Forest boss Aitor Karanka could look to freshen up the attack after six matches without a goal for the visit of Ipswich.