關於開心網的伺服器

1.開心網的主站採用了DNS輪詢技術，所謂DNS輪詢，就是一個網域名稱對應幾條A記錄，如開心網的主站有6台伺服器
DNS輪詢有一個缺點，如果網域名稱所指向的某一個台伺服器或幾台伺服器出現了問題（如Web伺服器停止服務)，則DNS輪詢無法判斷
C:/Users/caihuafeng>nslookup www.kaixin001.com
伺服器:  ns.crcbj.com
Address:  61.233.9.9

非權威應答:
名稱:    a.kaixin001.com
Addresses:  220.181.100.30
          220.181.100.35
          220.181.100.33
          220.181.100.34
          220.181.100.32
          220.181.100.31
Aliases:  www.kaixin001.com

2.a.kaixin001.com應該是網域名稱www.kaixin001.com的別名，也就是大家用http://a.kaixin001.com/同樣可以訪問開心網
C:/Users/caihuafeng>nslookup a.kaixin001.com
伺服器:  ns.crcbj.com
Address:  61.233.9.9

非權威應答:
名稱:    a.kaixin001.com
Addresses:  220.181.100.31
          220.181.100.35
          220.181.100.32
          220.181.100.34
          220.181.100.33
          220.181.100.30

3.查詢網域名稱伺服器ns.crcbj.com的一些情況
C:/Users/caihuafeng>nslookup -qt=ns ns.crcbj.com
伺服器:  ns.crcbj.com
Address:  61.233.9.9

crcbj.com
        primary name server = dns7.hichina.com
        responsible mail addr = hostmaster.hichina.com
        serial  = 2008070200
        refresh = 3600 (1 hour)
        retry   = 600 (10 mins)
        expire  = 604800 (7 days)
        default TTL = 3600 (1 hour)

4.查看開心網的郵件伺服器情況
根據nslookup查詢出的情況，我猜想mail1.kaixin001.com及mail2.kaixin002.com應該是開心網的郵件伺服器，開心網有上千萬的使用者，專門有兩台郵件伺服器是比較正常的;另外ns1.kaixin001.com ~ ns4.kaixin001.com這4台伺服器應該是開心網的網域名稱伺服器
C:/Users/caihuafeng>nslookup -qt=mx kaixin001.com
伺服器:  ns.crcbj.com
Address:  61.233.9.9

非權威應答:
kaixin001.com   MX preference = 10, mail exchanger = mail1.kaixin001.com
kaixin001.com   MX preference = 20, mail exchanger = mail2.kaixin001.com

kaixin001.com   nameserver = ns3.kaixin001.com
kaixin001.com   nameserver = ns1.kaixin001.com
kaixin001.com   nameserver = ns2.kaixin001.com
kaixin001.com   nameserver = ns4.kaixin001.com
mail2.kaixin001.com     internet address = 123.125.59.127
mail1.kaixin001.com     internet address = 119.161.132.228
ns2.kaixin001.com       internet address = 220.181.100.173
ns1.kaixin001.com       internet address = 123.103.102.240
ns3.kaixin001.com       internet address = 119.161.132.240
ns4.kaixin001.com       internet address = 123.125.57.13

5.開心網網域名稱解析過程的類比

在預設情況下nslookup使用的是我們在本機TCP/IP配置中的DNS伺服器進行查詢，但有時候我們需要指定一個特定的伺服器進行查詢實驗。這時候我們不需要更改原生TCP/IP配置，只要在命令後面加上指定的伺服器IP或者網域名稱就可以了。這個參數在我們對一台指定伺服器排錯是非常必要的，另外我們可以通過指定伺服器直接查詢授權伺服器的結果避免其他伺服器緩衝的結果

例如下面的測試在網域名稱伺服器f.gtld-servers.net下找不到網域名稱www.kaixin001.com解析結果，而在網域名稱伺服器ns1.kaixin001.com下能查詢到網域名稱www.kaixin001.com解析結果，說明網域名稱伺服器ns.kaixin001.com保持有網域名稱www.kaixin001.com的資訊
C:/Users/caihuafeng>nslookup -norecurse www.kaixin001.com f.gtld-servers.net
(root)  nameserver = c.root-servers.net
(root)  nameserver = h.root-servers.net
(root)  nameserver = b.root-servers.net
(root)  nameserver = f.root-servers.net
(root)  nameserver = d.root-servers.net
(root)  nameserver = a.root-servers.net
(root)  nameserver = j.root-servers.net
(root)  nameserver = l.root-servers.net
(root)  nameserver = g.root-servers.net
(root)  nameserver = e.root-servers.net
(root)  nameserver = k.root-servers.net
(root)  nameserver = i.root-servers.net
(root)  nameserver = m.root-servers.net
c.root-servers.net      internet address = 192.33.4.12
h.root-servers.net      internet address = 128.63.2.53
h.root-servers.net      AAAA IPv6 address = 2001:500:1::803f:235
b.root-servers.net      internet address = 192.228.79.201
f.root-servers.net      internet address = 192.5.5.241
f.root-servers.net      AAAA IPv6 address = 2001:500:2f::f
d.root-servers.net      internet address = 128.8.10.90
a.root-servers.net      internet address = 198.41.0.4
a.root-servers.net      AAAA IPv6 address = 2001:503:ba3e::2:30
j.root-servers.net      internet address = 192.58.128.30
j.root-servers.net      AAAA IPv6 address = 2001:503:c27::2:30
l.root-servers.net      internet address = 199.7.83.42
g.root-servers.net      internet address = 192.112.36.4
伺服器:  UnKnown
Address:  192.35.51.30

*** UnKnown 找不到 www.kaixin001.com: BAD ERROR VALUE

C:/Users/caihuafeng>nslookup -norecurse www.kaixin001.com ns1.kaixin001.com
DNS request timed out.
    timeout was 2 seconds.
伺服器:  UnKnown
Address:  123.103.102.240

名稱:    a.kaixin001.com
Addresses:  220.181.100.31
          220.181.100.30
          220.181.100.34
          220.181.100.32
          220.181.100.33
          220.181.100.35
Aliases:  www.kaixin001.com

同理輸入nslookup -norecurse www.kaixin001.com ns2.kaixin001.com,nslookup -norecurse www.kaixin001.com ns3.kaixin001.com,nslookup -norecurse www.kaixin001.com ns4.kaixin001.com也會有類似的解析結果，只不過Addresses後面的ip地址輸出順序不完全一樣。