Cisco IOS Forward / lookup balik nama

Saya ingin mengkonfigurasi Ciscos kami sehingga mereka dapat melakukan penerusan resolusi DNS, tetapi tidak membalikkan resolusi DNS dari CLI.

R01(config)#ip domain-name domain.local
R01(config)#ip name-server 10.1.1.1
R01(config)#ip domain-lookup

Konfigurasi itu membuat router melakukan pencarian maju ketika kita melakukan ping, dan membalikkan pencarian di bawah perintah yang menampilkan alamat ip. Ketika kita melakukan "show user", router melakukan pencarian terbalik untuk setiap alamat ip sumber. Sepertinya kita mendapatkan pencarian maju dan mundur ketika kita mengaktifkan "ip domain-lookup". Apakah ada cara untuk mematikan pencarian terbalik dan membiarkan pencarian maju aktif?

Apakah ada cara untuk mematikan pencarian terbalik dan membiarkan pencarian maju aktif?

Ringkasan:

Gunakan di no domain-lookupbawah line vty 0 4...

Detail:

Anda benar, perilaku default adalah untuk melakukan & cache pencarian maju / mundur untuk alamat dalam perintah acara. Konfigurasi ini mulai mirip dengan milik Anda ...

Perilaku dasar: Pencarian maju / mundur

HotCoffee#clear host *
HotCoffee#sh runn | i ip domain|ip name|^ +domain|NTP
Time source is NTP, 06:10:42.327 CDT Tue Aug 13 2013
ip domain name pennington.net
ip name-server 172.16.1.5
 domain-name pennington.net
HotCoffee#

Setelah menghapus cache host, tidak ada entri di dalamnya ...

HotCoffee#show host
Load for five secs: 0%/0%; one minute: 1%; five minutes: 1%
Time source is NTP, 06:11:46.864 CDT Tue Aug 13 2013

Default domain is pennington.net
Name/address lookup uses domain service
Name servers are 172.16.1.5

Codes: UN - unknown, EX - expired, OK - OK, ?? - revalidate
       temp - temporary, perm - permanent
       NA - Not Applicable None - Not defined

Host                      Port  Flags      Age Type   Address(es)
HotCoffee#

Melakukan show useratau pingmengisi cache host ...

HotCoffee#sh user
    Line       User       Host(s)              Idle       Location
* 66 vty 0     cisco      idle                 00:00:00 tsunami.pennington.net

  Interface    User               Mode         Idle     Peer Address

HotCoffee#ping flame
Translating "flame"...domain server (172.16.1.5)

Translating "flame"...domain server (172.16.1.5) [OK]

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.1, timeout is 2 seconds:
.!!!!
Success rate is 80 percent (4/5), round-trip min/avg/max = 1/2/4 ms
HotCoffee#

Sekarang ada entri host untuk pingtarget dan show user...

HotCoffee#sh hosts
Load for five secs: 1%/0%; one minute: 0%; five minutes: 0%
Time source is NTP, 06:16:32.811 CDT Tue Aug 13 2013

Default domain is pennington.net
Name/address lookup uses domain service
Name servers are 172.16.1.5

Codes: UN - unknown, EX - expired, OK - OK, ?? - revalidate
       temp - temporary, perm - permanent
       NA - Not Applicable None - Not defined

Host                      Port  Flags      Age Type   Address(es)
tsunami.pennington.net    None  (temp, OK)  0   IP    172.16.1.5
flame.pennington.net      None  (temp, OK)  0   IP    172.16.1.1
flame                     None  (temp, UN)  0  IPv6 
HotCoffee#

Solusi: Only Forward lookups

Gunakan di no domain-lookupbawah vty / console lines untuk membatasi perilaku iOS hanya meneruskan pencarian ...

HotCoffee#conf t
Enter configuration commands, one per line.  End with CNTL/Z.
HotCoffee(config)#line vty 0 4
HotCoffee(config-line)#no domain-lookup
HotCoffee(config-line)#end
HotCoffee#

Pertama saya menghapus cache host untuk tes bersih ...

HotCoffee#clear host *
HotCoffee#
HotCoffee#

show user sebelumnya melakukan reverse-lookup pada 172.16.1.5 serta mengisi cache host, tetapi tidak terjadi sekarang ...

HotCoffee#sh user
Load for five secs: 1%/0%; one minute: 0%; five minutes: 0%
Time source is NTP, 06:20:00.250 CDT Tue Aug 13 2013

    Line       User       Host(s)              Idle       Location
* 66 vty 0     cisco      idle                 00:00:00 172.16.1.5   <----

  Interface    User               Mode         Idle     Peer Address

HotCoffee#
HotCoffee#sh host
Load for five secs: 2%/0%; one minute: 0%; five minutes: 0%
Time source is NTP, 06:20:06.729 CDT Tue Aug 13 2013

Default domain is pennington.net
Name/address lookup uses domain service
Name servers are 172.16.1.5

Codes: UN - unknown, EX - expired, OK - OK, ?? - revalidate
       temp - temporary, perm - permanent
       NA - Not Applicable None - Not defined

Host                      Port  Flags      Age Type   Address(es)
                                                                    <----
HotCoffee#

Hanya untuk menunjukkan bahwa pencarian maju masih berfungsi ...

HotCoffee#
HotCoffee#ping flame
Translating "flame"...domain server (172.16.1.5)

Translating "flame"...domain server (172.16.1.5) [OK]

Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 172.16.1.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 1/1/4 ms
HotCoffee#
HotCoffee#
HotCoffee#
HotCoffee#sh hosts
Load for five secs: 0%/0%; one minute: 0%; five minutes: 0%
Time source is NTP, 06:25:43.237 CDT Tue Aug 13 2013

Default domain is pennington.net
Name/address lookup uses domain service
Name servers are 172.16.1.5

Codes: UN - unknown, EX - expired, OK - OK, ?? - revalidate
       temp - temporary, perm - permanent
       NA - Not Applicable None - Not defined

Host                      Port  Flags      Age Type   Address(es)
tsunami.pennington.net    None  (temp, OK)  0   IP    172.16.1.5
flame.pennington.net      None  (temp, OK)  0   IP    172.16.1.1
flame                     None  (temp, UN)  0  IPv6 
HotCoffee#