Trying to pull repository docker.io/library/nextcloud …
error parsing HTTP 408 response body: invalid character ‘<’ looking for beginning of value

[root@docker-registry ~]# yum install bind-utils // 安装dig工具
[root@docker-registry ~]# dig @114.114.114.114 registry-1.docker.io

; < <>> DiG 9.9.4-RedHat-9.9.4-61.el7_5.1 < <>> @114.114.114.114 registry-1.docker.io
; (1 server found)
;; global options: +cmd
;; Got answer:
;; ->>HEADER< <- opcode: QUERY, status: NOERROR, id: 51198
;; flags: qr rd ra; QUERY: 1, ANSWER: 8, AUTHORITY: 0, ADDITIONAL: 1

;; OPT PSEUDOSECTION:
; EDNS: version: 0, flags:; udp: 4096
;; QUESTION SECTION:
;registry-1.docker.io. IN A

;; ANSWER SECTION:
registry-1.docker.io. 31 IN A 34.206.236.31
registry-1.docker.io. 31 IN A 54.175.43.85
registry-1.docker.io. 31 IN A 34.205.207.96
registry-1.docker.io. 31 IN A 34.233.151.211
registry-1.docker.io. 31 IN A 52.70.175.131
registry-1.docker.io. 31 IN A 34.200.28.105
registry-1.docker.io. 31 IN A 54.165.149.19
registry-1.docker.io. 31 IN A 34.201.236.93

;; Query time: 10 msec
;; SERVER: 114.114.114.114#53(114.114.114.114)
;; WHEN: Wed Oct 31 11:18:55 CST 2018
;; MSG SIZE rcvd: 177

选择上面命令执行结果中的一组解析放到本机的/etc/hosts文件里做映射

[root@docker-registry ~]# vim /etc/hosts
54.175.43.85 registry-1.docker.io

接着再进行docker pull镜像下载操作

[root@docker-registry ~]# docker pull centos
Using default tag: latest
Trying to pull repository docker.io/library/centos …

参考
https://blog.51cto.com/u_14159501/2338204