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Mario_Franco's avatar
Mario_Franco
Icon for Altocumulus rankAltocumulus
Sep 20, 2023

Implementing F5 DNS and Creating Custom CNAME Redirects

We are currently implementing a solution in Azure and have encountered some DNS-related issues. I think it's a good idea to implement F5 DNS. However, I wonder if we can create an iRule to set up a C...
application delivery
dns
iRules
xuwen's avatar
xuwen
Icon for Cumulonimbus rankCumulonimbus
Sep 22, 2023
when DNS_REQUEST priority 500 {
    set original_name [DNS::question name]
    if { [string tolower $original_name] ends_with "example.com" } {
        set modified_name [string map {"example.com" "example.2.com"} [string tolower $original_name]]
        # DNS::question name $modified_name
        set cname_record "${original_name}. 300 IN CNAME ${modified_name}."
        log local0. "cname_record is ${cname_record}"
        set new_rr [DNS::rr ${cname_record}]
        # log local0. "$new_rr"
        DNS::answer clear
        DNS::answer insert $new_rr
        DNS::header aa 1
        DNS::header rd 0
        DNS::header ra 0
        DNS::header ad 0
        DNS::return
    }
}

 

 

[root@NF42GTT1-A3:Active:Standalone] config # dig @172.16.53.53 www22.example.com

; <<>> DiG 9.11.31 <<>> @172.16.53.53 www22.example.com
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 60738
;; flags: qr aa; QUERY: 1, ANSWER: 1, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;www22.example.com. IN A

;; ANSWER SECTION:
www22.example.com. 300 IN CNAME www22.example.2.com.

;; Query time: 4 msec
;; SERVER: 172.16.53.53#53(172.16.53.53)
;; WHEN: Fri Sep 22 15:44:52 CST 2023
;; MSG SIZE rcvd: 76