Заметки сисадмина » How to restore deleted DNS SRV records?

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How to restore deleted DNS SRV records?

SRV (Service Record) is a type of resource record supported in the database of the DNS server. It records services running on each computer.

What is SRV record?

Generally, it is an application when set up for Microsoft’s Active Directory. DNS can be independent of Active Directory, but Active Directory must have the help of DNS to work. In order for the Active Directory to work properly, the DNS server must support SRV, which maps the service name to the server that provides the service. Active Directory clients and domain controllers use SRV resource records to determine the IP address of the domain controller.

SRV record function includes (based on their grouping in DNS console):


In this group, SRV records are collected based on their status. Various states include DC, domain call, GC, and PDC. DC and GC are divided by site, so that the AD client can quickly know where to look for local services. “Domain call” is used to support replication. Each DC gets a GUID, which will be used when calling replication. The PDC entry contains the SRV record of the DC set as the PDC simulator.


The site represents a high-speed connection area. After the DC index is established based on the site affiliation of the DC, the client can check _SITES to find local services without sending their LDAP query requests over the WAN. The standard LDAP query port is 389, and the global catalog query uses 3268.


In this group, all DCs in the DNS zone are collected. If the client cannot find their specific site, or any DC with a local SRV record does not respond, and needs to find a DC elsewhere in the network, these clients should be placed in this group.


Keberos v5 allows clients to use “connectionless” services to obtain tickets and change passwords. This is done through the UDP port corresponding to the TCP port of the same service. Specifically, the ticket exchange uses UDP port 88, and the password change uses 464

Who will register SRV records?

All DCs and GCs will find DNS servers to register their SRV records when they are generated.

What’s the advantage of SRV for customers?

Users only need to know which domain to find a computer that provides the target service except for the target FQDN, they can easily find the server and obtain its IP.

For this function, since the customers who need it are rare, Eranet does not support it temporarily.

How to repair DNS SRV records?

If you delete the SRV record in DNS by mistake, you can restore it by following the two simple steps:

1)Create two new zones in the DNS forward lookup zone: abc.com (your domain name) and _msdcs.abc.com


And the SRV records can be quickly restored.

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