Dig Domains
; <<>> DiG Dig.Domains <<>> any alt51.googlemail.com
;; Got answer:
;; ->>HEADER<<- opcode: QUERY, status: NOERROR, id: 53687
;; flags: qr rd ra; QUERY: 1, ANSWER: 17, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 512
;; QUESTION SECTION:
;alt51.googlemail.com.	IN ANY

;; ANSWER SECTION:
alt51.googlemail.com.	299 IN A 64.233.165.19
alt51.googlemail.com.	299 IN A 64.233.165.17
alt51.googlemail.com.	299 IN A 64.233.165.83
alt51.googlemail.com.	299 IN A 64.233.165.18
alt51.googlemail.com.	299 IN AAAA 2a00:1450:4010:c08::12
alt51.googlemail.com.	21599 IN NS ns3.google.com.
alt51.googlemail.com.	21599 IN NS ns2.google.com.
alt51.googlemail.com.	21599 IN NS ns1.google.com.
alt51.googlemail.com.	599 IN MX 10 alt1.gmail-smtp-in.l.google.com.
alt51.googlemail.com.	599 IN MX 20 alt2.gmail-smtp-in.l.google.com.
alt51.googlemail.com.	599 IN MX 5 gmail-smtp-in.l.google.com.
alt51.googlemail.com.	21599 IN NS ns4.google.com.
alt51.googlemail.com.	21599 IN CAA 0 issue "pki.goog"
alt51.googlemail.com.	59 IN SOA ns1.google.com. dns-admin.google.com. (
				208817945  ; serial
				900        ; refresh (15 minutes)
				900        ; retry (15 minutes)
				1800       ; expire (30 minutes)
				60         ; minimum (1 minute)
				)
alt51.googlemail.com.	599 IN MX 40 alt4.gmail-smtp-in.l.google.com.
alt51.googlemail.com.	599 IN MX 30 alt3.gmail-smtp-in.l.google.com.
alt51.googlemail.com.	299 IN TXT "v=spf1 redirect=_spf.google.com"

;; Query time: 27 msec
;; SERVER: 8.8.8.8#53(8.8.8.8)
;; WHEN: Wed Aug 15 12:23:59 EDT 2018
;; MSG SIZE  rcvd: 453


Check the DNS Propagation for alt51.googlemail.com