Dodge bonus

Overview
A Dodge bonus is a bonus to Armor Class. Note that dodge bonuses can stack with each other, contrary to most other Armor Class bonus types. Identical magnitude dodge bonuses from treasure do not stack in DDO. So a +3 dodge bonus on Dragontouched armor will not stack with a +3 dodge bonus from Chattering Ring. But a +4 dodge bonus on the Icy Raiment will stack with the +3 from either Dragontouched, Chattering Ring. (Except that Dragontouched Armor and Icy Raiments both use the same slot.)

Feats

 * Combat expertise +5 (also gives a -5 penalty to attack rolls)
 * Defensive fighting +2 (also gives a -4 penalty to attack rolls)
 * Dodge feat +1
 * Mobility feat/item +4 (only while tumbling)
 * Uncanny dodge +4 (rogue and barbarian only)
 * Improved uncanny dodge +6 (rogue and barbarian only)
 * Inspire Heroics +4 (level 15 bard buff)

Enhancements

 * Favoured Defense I to III +2-4 (Ranger only, vs. favoured enemies)


 * Fighter's Mobility I to II +1-2 (fighter only, only while tumbling; requires Mobility feat)
 * Giant Dodger I +4 vs. attacks from giant-type creatures (dwarf only)

Items

 * Alchemical Armor Ritual +1 (Stone of Change Crafting)
 * Alchemical Shield Ritual +1 (Stone of Change Crafting)
 * Chaosgarde bracers +2 (lawful alignment only, from Xorian Cipher)
 * Chattering Ring +3 (The Titan Awakes raid loot)
 * Dragontouched Armor +3 (Sovereign Rune Property)
 * Icy Raiment outfit +4 (drops in the Garamol Chest in The Subterrane - Central)
 * Cloak of Night (Level 16) +1 or Epic Cloak of Night +2 (from Mabar Endless Night Festival)

Racial

 * Dwarf +4 vs. attacks from giant-type creatures (dwarf only)

Spells

 * Haste +1
 * Haste Guard proc effect +1

Dodge Bonus Limitations
It is written in DDO user manual (p.74) and in PnP book (need citation), that dodge bonuses only stack up to a maximum of 10. But that is not really the case in game. You can benefit from more than 10 dodge bonus. It is unclear whether it is intentional or not.

Dodge Bonus Item Stacking

 * "The dodge bonuses for multiple chattering rings are being treated as coming from the same source so they do not stack." - developer Grral
 * "Identical magnitude dodge bonuses from treasure do not stack in DDO. (With the exception of the Eldritch Ritual Shield/Armor improvements, when we renamed those to "Dodge". We'll rename those yet again to be clearer that those stack with everything but themselves.) This is an intentional deviation from the basic D&D rules." - developer Eladrin, forums.ddo.com

Other AC Bonus Types
Other common bonuses to your armor class are armor bonus, shield bonus, deflection bonus, dexterity bonus, natural armor bonus, and miscellaneous bonus.