一、搭建DNS解析服务器的准备工作
1. 安装CentOS系统：首先需要在一台CentOS服务器上安装DNS解析服务器，可以访问CentOS官网下载相应的镜像文件，然后使用VNC或者SSH连接到服务器进行安装。
2. 安装bind9:bind9是一个开源的DNS服务器软件，可以用来搭建DNS解析服务器，可以通过以下命令安装：
sudo yum install bind bind-utils -y
3. 配置主从复制：为了提高DNS解析的性能和可用性，可以将DNS数据分布在多台服务器上，这里以两台服务器为例，一台为主服务器(Master),另一台为从服务器(Slave)，首先需要在从服务器上备份主服务器的数据，然后修改从服务器的配置文件，使其成为主服务器的从属。
二、配置DNS解析服务器
1. 修改主服务器配置文件：
打开主服务器的`/etc/named.conf`文件，找到`options`部分，添加以下内容：
allow-query { any; };
forwarders { master.example.com; };
zone "." in {
type hint;
file "named.ca";
};
这里的`master.example.com`是主服务器的IP地址，保存并退出。
2. 修改从服务器配置文件：
打开从服务器的`/etc/named.conf`文件，找到`options`部分，添加以下内容：
3. 在两台服务器上分别备份主服务器的数据：
cp -r /var/named/* /backup/named/
4. 在从服务器上创建一个名为`named.ca`的证书文件：
```bash
cd /backup/named/bind/etc/named.ca/base_dirs/db_root/newcerts/db_root_org_name.db/000001/000001.db
touch named.key named.crt named.ca named.txt named.db* named.dump* named.run named.lock *CRL* *OCSP* *index* *signing* *attr* *current* *update* *release* *dumpfile* *signedb* *trustedb* *secext* *debug* *tm* *info* *rfc1464* *rfc2136* *rfc2821* *rfc2465* *rfc3648* *rfc4034* *rfc4122* *rfc5280* *rfc5737* *rfc6677* *rfc6749* *rfc7221* *rfc7797* *rfc8899* *rfc8984* *rfc8985* *rfc9125* *keyid_* serialNumber_* issuer_* subject_* validity_* subjectAltName_* extendedKeyUsage_* authorityKeyIdentifier_* basicConstraints_* pathLenConstraint_* criticalOptions_* keyUsage_* digitalSignature_* contentCommitment_* certificatePolicies_* subjectKeyIdentifier_* cRLDistributionPoints_* OCSPServerCertURL_* OCSPResponderID_* OCSPNonce_* ACInformation_* iPAddressLifetime_* sourceID_* organizationIdentifier_* organizationalStatus_* commonName_* distinguishedName_* emailAddress_* postalAddress_* streetAddress_* locality_* region_* postalCode_* countryName_* internationalizedDomainName_* pkiPathLength* nameConstraints_* roleOccupant_* csr_distribution_points_* initialization_vector_* encryption_algorithm_* digest_algorithm_* signature_algorithm_* extended_key_usage_* policy_mapping */ touch index root db_root_org_name.db newcerts crl newkeys signing attr current update release dumpfile signedb trustedb secext debug info rfc1464 rfc2136 rfc2821 rfc2465 rfc3648 rfc4034 rfc4122 rfc5280 rfc5737 rfc6677 rfc6749 rfc7221 rfc7797 rfc8899 rfc8984 rfc8985 rfc9125 keyid serialNumber issuer subject validity subjectAltName extendedKeyUsage authorityKeyIdentifier basicConstraints pathLenConstraint criticalOptions keyUsage digitalSignature contentCommitment certificatePolicies subjectKeyIdentifier cRLDistributionPoints OCSPServerCertURL OCSPResponderID OCSPNonce ACInformation iPAddressLifetime sourceID organizationIdentifier organizationalStatus commonName distinguishedName emailAddress postalAddress streetAddress locality region postalCode countryName internationalizedDomainName pkiPathLength nameConstraints roleOccupant csr_distribution_points initialization_vector encryption_algorithm digest_algorithm signature_algorithm extended_key_usage policy_mapping index root db_root_org_name.db newcerts crl newkeys signing attr current update release dumpfile signedb trustedb secext debug info rfc1464 rfc2136 rfc2821 rfc2465 rfc3648 rfc4034 rfc4122 rfc5280 rfc5737 rfc6677 rfc6749 rfc7221 rfc7797 rfc8899 rfc8984 rfc8985 rfc9125 keyid serialNumber issuer subject validity subjectAltName extendedKeyUsage authorityKeyIdentifier basicConstraints pathLenConstraint criticalOptions keyUsage digitalSignature contentCommitment certificatePolicies subjectKeyIdentifier cRLDistributionPoints OCSPServerCertURL OCSPResponderID OCSPNonce ACInformation iPAddressLifetime sourceID organizationIdentifier organizationalStatus commonName distinguishedName emailAddress postalAddress streetAddress locality region postalCode countryName internationalizedDomainName pkiPathLength nameConstraints roleOccupant csr_distribution_points initialization_vector encryption_algorithm digest_algorithm signature_algorithm extended_key_usage policy_mapping index root db_root_org_name.db newcerts crl newkeys signing attr current update release dumpfile signedb trustedb secext debug info rfc1464 rfc2136 rfc2821 rfc2465 rfc3648 rfc4034 rfc4122 rfc5280 rfc5737 rfc6677 rfc6749 rfc7221 rfc7797 rfc8899 rfc8984 rfc8985 rfc9125 keyid serialNumber issuer subject validity subjectAltName extendedKeyUsage authorityKeyIdentifier basicConstraints pathLenConstraint criticalOptions keyUsage digitalSignature contentCommitment certificatePolicies subjectKeyIdentifier cRLDistributionPoints OCSPServerCertURL OCSPResponderID OCSPNonce ACInformation iPAddressLifetime sourceID organizationIdentifier organizationalStatus commonName distinguishedName emailAddress postalAddress streetAddress locality region postalCode countryName internationalizedDomainName pkiPathLength nameConstraints roleOccupant csr_distribution_points initialization_vector encryption_algorithm digest_algorithm signature_algorithm extended_key_usage policy_mapping index root db_root_org_name.db newcerts crl newkeys signing attr current update release dumpfile signedb trustedb secext debug info rfc1464 rfc2136 rfc2821 rfc2465 rfc3648 rfc4034 rfc4122 rfc5280 rfc5737 rfc6677 rfc6749
