According to Official Guinness Records,
The fastest men's IAAF marathon road relay is 1 hour 57 minutes 6 seconds, by a team representing Kenya (Josephat Ndambiri, Martin Mathathi, Daniel Mwangi, Mekubo Mogusu, Onesmus Nyerere, John Kariuki) at the International Chiba Ekiden in Chiba, Japan, on 23 November 2005. Originating from the Japanese long-distance Ekiden relay, a road relay team comprises six athletes running set legs of 5 km, 10 km, 5 km, 10 km, 5 km and 7.195 km over a marathon course.
For a complete list of 2005 records, please visit 2005 Guinness Records in Japan.