WotLK Is DK good tanking class for beginner?

[Tyrial]

So I want to roll a tank on Icecrown and I was thinking about DK, because I wouldn't have to level all the way from level 1 and because it would be a fresh experience for me, as I have never played a DK. However I have never played a tank and from the other threads I read, people suggest that paladin is the best choice - safe and easy tank on 3.3.5a. (I have no interest in playing bear/warr) On the other hand DK supposedly has to keep eye on rune management, has problems with AoE threat and doesn't have many defensive CDs.

What would you suggest me friends? Shall I follow my plan and go with DK or should I start leveling paladin? I am a casual player so I'm looking for a reliable tank mainly for 5man instances and raids second.

[Thydus]

Go Frost Tank, = good instant aoe threat heavy armor cd etc.

[Zelda1220]

As Thydus broke it down for you, Frost Tank is a perfect place for tank beginners.

I honestly think Frost Tank is almost better than Prot Paladins in some aspect.

[DamnOriginal]

On the other hand DK supposedly has to keep eye on rune management, has problems with AoE threat and doesn't have many defensive CDs.

Some of this is completely wrong. First of all, when people talk about DKs having bad AOE threat, they're referring specifically to blood, as frost is great at AOE. When it comes to blood, the reason people say it has "bad" AOE threat is because a lot of blood DKs don't spec into a very powerful AOE tanking talent called Morbidity in the unholy tree and apparently there's a bug that causes Death and Decay, the main AOE tanking tool for blood, to generate much less threat than it should. The result of both of those factors is why blood gets the bad AOE tank rep, since not only is it bugged but the people that play the spec don't really try to circumvent the bug. If you spec into morbidity, adopt a more proactive tab-targeting tanking style akin to what most warrior tanks are used to and don't rely on DnD to hand you all the threat on a silver platter, you will have absolutely no problems even as blood.

Second, Death Knights have the most and most frequent defensives out of any tank. Just a little comparison to paladins, who get divine protection (2min), Lay on Hands (10mins) and Divine Sacrifice (2min), the last of which is more of a liability than a proper cooldown. A Death Knight in turn is going to have Icebound Fortitude (2mins), Anti-Magic Shell (45sec), Rune Tap (30sec), Vampiric Blood/Unbreakable Armor/Bone Shield (1min), Death Pact (3min), Empower Rune Weapon (5mins) and Army of the Dead (10min). This does not mean that Death Knights are somehow better than paladins but it does make Death Knights a much more active tank than paladins.

As for runes, Death Knights definitely have to pay more attention to their resources than any other tank. It's important to get a good feel of how your runes recharge and what kind of runes your spec generates or uses in order to always be able to use the right abilities, it's different to the generally spammy nature of other tanks but the more you play it, the easier and more natural it feels.

Now, considering what you said about being completely new to tanking in general and wanting to focus primarily on dungeons, I think you're gonna have a much greater success as paladin. Paladins are both easy to play and extremely good in dungeons as they have perfect AOE threat at the press of 1 button and are a block tank, which can result in them taking almost or literally no physical damage. There's no reason you can't try Death Knight if you really like the sound and feel of the class more than the other options, you wont be gimped, you're just gonna have to git gud.

[Tyrial]

Thank you all for informative responses. I will probably roll a paladin tank and eventually try out frost/blood DK when I get some tanking experience under my belt.

[Brightwing]

I'm glad that you went for DamnOriginal answer instead of the other ones. I was about to said something similar to the fourth paragraph.
You mentioned that you don't want to level from level 1. And that you would be new to Death Knights and Tanking, I think that you should play Death Knight, without trying to Tank, I guess level it up in the common way, DPS specced, and once you hit level 80 and feel confortable with the class and managing runes and all, then you should start focusing on DK Tanking.
See if you like the class and Tanking, if you don't like the class or maybe you don't want to manage the class but you really liked what Tanking does, then you should think about leveling a Paladin.
To save time and effort, of course, if you don't mind playing the game and enjoying it then go ahead and level up as Protection Paladin, pulling a lot of mobs and mentioning your level and spec on Global chat, people will always whisper you for Dungeons.

Good luck!