The official qualification draw doesn't take place until July 25, but a few nations will already have been eliminated by then. The first matches will be played in Asia tomorrow!
Asian Football Confederation -
46 nations, 4 or 5 places
The first round of AFC qualifying begins tomorrow with the 12 lowest seeded teams drawn into home-and-away ties. Second leg will be on the 17th of March.
India vs. Nepal
Yemen vs. Pakistan
Timor-Leste vs. Mongolia
Cambodia vs. Macau
Chinese Taipei vs. Brunei
Sri Lanka vs. Bhutan
The second round will be the six winners of these ties, plus the 34 other teams, which will be will be divided into eight groups of five to play home-and-away round-robin matches, where the eight group winners and the four best group runners-up will advance to the third round. Some serious stomp-fests will probably happen in this round.
Third round will have will be divided into two groups of six to play home-and-away round-robin matches. Top two in each group will go to the World Cup, third placed team will have a play-off, winner of that will have another play-off against a team from another confederation.
Confederation of African Football -
54 nations, 5 places
Qualification begins in October 2015, first, there will be three home-and away rounds to get down to 20 teams, these will then be divided into five groups for Round 4. Each group winner goes to the World Cup.
Union of European Football Associations -
52 nations, 13 places
Draw to be held July 25. Qualifying process yet to be confirmed, but it will probably be the same as always (8-9 groups, winner qualifies, 2nd plays play-off). Although with 13 out of 52 qualifying, you could also play in groups of four.
Confederation of North, Central American and Caribbean Association Football -
35 nations, 3 or 4 places
First round runs from 22nd to 29th of March. Bottom 14 teams are paired up, winners will join teams ranked 9-21 (including CANADA) in the second round.
First round match-ups:
Bahamas vs.Bermuda
British Virgin Islands vs. Dominica
Barbados vs. U.S. Virgin Islands
Saint Kitts and Nevis vs. Turks and Caicos Islands
Nicaragua vs. Anguilla
Belize vs. Cayman Islands
Curaçao vs. Montserrat
Second round:
Saint Vincent and the Grenadines vs. Guyana
Antigua and Barbuda vs. Saint Lucia
Puerto Rico vs. Grenada
Canada vs. (British Virgin Islands or Dominica)
Dominican Republic vs. (Belize or Cayman Islands)
Guatemala vs. (Bahamas or Bermuda)
Aruba vs. (Barbados or U.S. Virgin Islands)
(Turks and Caicos Islands or Saint Kitts and Nevis) vs. El Salvador
(Curaçao or Montserrat) vs. Cuba
(Nicaragua or Anguilla) vs. Suriname
Third round
Jamaica and Haiti will join the ten winners of Round 2, and play a home-and-away tie.
Fourth round
A total of 12 teams (teams ranked 1–6 (USA#1) and six third round winners) will be divided into three groups of four to play home-and-away round-robin matches, top two go to Round 5.
Fifth round
THE HEX. One group of six. Three qualify for Russia, fourth goes to the inter-continental play-off.
Confederación Sudamericana de Fútbol -
10 nations, 4 or 5 places
Single table, home-and-away. Top 4 to Russia, 5th to the play-off. Starting in October 2015.
Oceania Football Confederation -
11 places, 0 or 1 place
Short summary:
Longer version:
First round: American Samoa, Cook Islands, Samoa, and Tonga will play a 'preliminary round-robin tournament' at a single venue. The winner will advance to the second round.
Second round: Two groups of four, home-and-away. Top two go to Round 3.
Third round: One group of four. New Zealand advances to the inter-continental playoff.
The draw for the inter-federation playoffs to decide the final qualifiers will also take place on July 25.