求救！有关google收录的问题

我有几个网站自打更换了一个独立IP空间后，其中一个站Google收录变没了，但同IP的其它几个站还都收录良好。查了下该站的日志，有关Google爬虫的记录有几条如下：
[30/Apr/2013:11:10:42 +0800] "GET /robots.txt HTTP/1.0" 404 208 "-" "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" 203.208.60.116
[30/Apr/2013:11:10:42 +0800] "GET / HTTP/1.0" 200 51140 "-" "SAMSUNG-SGH-E250/1.0 Profile/MIDP-2.0 Configuration/CLDC-1.1 UP.Browser/6.2.3.3.c.1.101 (GUI) MMP/2.0 (compatible; Googlebot-Mobile/2.1; +http://www.google.com/bot.html)" 188.40.120.19
[30/Apr/2013:11:45:36 +0800] "GET / HTTP/1.0" 200 51140 "-" "DoCoMo/2.0 N905i(c100;TB;W24H16) (compatible; Googlebot-Mobile/2.1; +http://www.google.com/bot.html)" 123.125.71.57

[01/May/2013:14:03:10 +0800] "GET / HTTP/1.0" 200 51140 "-" "Mozilla/5.0 (Windows NT 6.1; rv:6.0) Gecko/20110814 Firefox/6.0 Google (+https://developers.google.com/+/web/snippet/)" 66.249.84.57
[01/May/2013:14:03:11 +0800] "GET /favicon.ico HTTP/1.0" 404 209 "-" "Mozilla/5.0 (Windows NT 6.1; rv:6.0) Gecko/20110814 Firefox/6.0 Google (+https://developers.google.com/+/web/snippet/)" 118.183.211.245
[01/May/2013:15:48:35 +0800] "GET /robots.txt HTTP/1.0" 404 208 "-" "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" 203.208.60.117
[01/May/2013:15:48:36 +0800] "GET / HTTP/1.0" 200 51140 "-" "Mozilla/5.0 (compatible; Googlebot/2.1; +http://www.google.com/bot.html)" 61.135.190.103

请问同仁，上面频繁出现的 200 51140 是什么意思，是不是有造成不收录的原因，请点拔一下。

回复讨论(解决方案)

另外，请教，Google爬虫的响应码都有哪些呢

做一个 robots.txt 放在根目录
具体格式没研究过，但很多SEO文章都有说这个，不难找到

200是http状态码，表示正常返回
51140不清楚，看你自己服务器log的格式说明（字节数？）