iv
DHCP snooping configuration examples ····················································································································· 83
DHCP snooping configuration example ············································································································· 83
DHCP snooping Option 82 support configuration example ············································································ 83
Configuring IPv4 DNS ··············································································································································· 85
Overview ········································································································································································· 85
Static domain name resolution ····························································································································· 85
Dynamic domain name resolution ······················································································································· 85
Configuring the IPv4 DNS client ·································································································································· 87
Configuring static domain name resolution ········································································································ 87
Configuring dynamic domain name resolution ·································································································· 87
Displaying and maintaining IPv4 DNS ························································································································ 88
IPv4 DNS configuration examples ······························································································································· 88
Static domain name resolution configuration example ····················································································· 88
Dynamic domain name resolution configuration example ··············································································· 89
Troubleshooting IPv4 DNS configuration ···················································································································· 92
Symptom ································································································································································· 92
Solution ··································································································································································· 92
Configuring NAT ························································································································································ 93
Overview ········································································································································································· 93
NAT control ···························································································································································· 94
NAT operation ······················································································································································· 94
Configuration restrictions and guidelines ···················································································································· 97
NAT configuration task list ············································································································································ 97
Configuring address translation ··································································································································· 98
Configuring static NAT ········································································································································· 98
Configuring dynamic NAT ··································································································································· 99
Configuring an internal server ···································································································································· 101
Introduction to internal server ····························································································································· 101
Configuration procedure ···································································································································· 101
Configuring DNS mapping ········································································································································· 102
Configuring NAT aging time ······································································································································ 102
Configuring NAT ALG ················································································································································· 102
Configuring NAT logging ··········································································································································· 103
Introduction to NAT logging ······························································································································ 103
Enabling NAT logging ········································································································································ 103
Exporting NAT logs ············································································································································· 103
Setting NAT connection limit ······································································································································ 105
Introduction to connection limit ·························································································································· 105
Configuring connection limit ······························································································································ 105
Enabling aging out NAT entries upon master link failure ························································································ 107
Displaying and maintaining NAT······························································································································· 107
NAT configuration examples ······································································································································ 109
One-to-one static NAT configuration example ································································································· 109
Dynamic NAT configuration example ··············································································································· 110
Internal server configuration example ··············································································································· 111
NAT DNS mapping configuration example ····································································································· 112
Exporting NAT logs to the information center ·································································································· 113
Exporting NAT logs to log server ······················································································································ 115
Troubleshooting NAT ··················································································································································· 116
Symptom 1 ··························································································································································· 116
Solution ································································································································································· 116
Symptom 2 ··························································································································································· 116
